Unofficial Garmin GPS FAQ (formerly Garmin GPS 45/40/38 FAQ) ============================================================ V 1.101 Mar 29, 1997 V 1.101.a Feb 19,2008 (1.101.a is 1.101 with email address removed --tim) Compiled by Lane A. Holdcroft Garmin GPS FAQ Copyright 1995, 1996, 1997 by Lane A. Holdcroft. Original contributors retain their copyright for all of their contributions. This document is not in any way endorsed by Garmin International. I am not affiliated with Garmin or any of their retailers. This Garmin GPS FAQ is targeted primarily at the GPS 45/45XL, 40, 38, II, and 12XL but also has lots of information on the GPS 89, 90, 120, and 175. Most of this FAQ applies to other Garmin units as well. This does not have any significant information about Garmin's professional surveying equipment or permanently mounted aircraft GPS's. | Garmin finally has their website up and working! It is: http://www.garmin.com | If you want to print this out and have the columns line up, use a non-proportionally spaced font such as "Courier". Also note that this document is huge! | The GPS 12XL was just released in January 1997. It is like the GPS 40 but has 12 channels for better performance in marginal conditions such as trees and it does NOT have the 90 knot speed limit. As of March 1997, it is still difficult to obtain due to limited supply and large demand. There are numerous user reports in the section "GPS 12XL". | The GPS II is sort of like a differently shaped GPS 45XL which includes map zoom buttons. It was released in November 1996. | The GPS 38 (released Feb 1996), is very similar to the GPS 40. However, the 38 has improved software, no external antenna connector, no beeper, no video tape, and a lower price. See the new section "GPS 38". The GPS 40 is being discontinued but is still available. It was the predecessor to the GPS 38. However the 40 had an external antenna connector. | The GPS 45 was Garmin's first really small handheld GPS. It is probably the most popular GPS sold to date, but will likely be surpassed by the cheaper GPS 38. | The GPS 45XL (released July 1996) is a GPS 45 (April 1994) with the GPS 38 software enhancements. Almost all references to the GPS 45 in this FAQ also apply to the GPS 45XL except some of the software specifics. | The older GPS 50, 65, and 75 have many internal similarities (and some software compatibility) to the GPS 45/40/38. The GPS 89 and 90 are very similar to the GPS 45 but have different software and additional non-volatile memory for their aero navigation database. Among other things, the GPS 89 has a much less detailed navigation database than the GPS 90. The GPS 120 (released late 1995) has almost identical software to the GPS 45 but a mobile mount, external antenna and a much larger display. The GPS 130 is Garmin's 12 channel mobile mount GPS unit with a map. It has a case similar to the GPS 120. It started shipping in the Spring of 1996. The GPSMAP 175 is Garmin's large 12 channel handheld announced in July 1996. It is large for a handheld but has a nice built-in map of the world and can take detailed map cartridges. It started shipping in September 1996. | The GPS 195 is the aviation model of the GPSMAP 175. CAUTION: It seems like it should go without saying, but a GPS unit does NOT replace common sense! If there is any possibility of getting lost, you should have a MAP AND COMPASS and KNOW HOW TO USE THEM! An electronic instrument is not failproof. Also, GPS units do not work without good batteries. | ====================================================================== TABLE OF CONTENTS: ----------------- 1.00 ABOUT THIS FAQ: -General FAQ info? -FAQ revision history? -Suggestions for improvement? 2.00 GARMIN PRODUCTS: | -Garmin GPS models? -Garmin accessories? 3.00 GENERAL GARMIN QUESTIONS: -What are some key features of the Garmin GPS 45/40/38/II? -What are the disadvantages of the GPS 45/40/38/II? -Comparison of the GPS 38/40/45/45XL/II/89/90/12XL? | -What are the differences between the GPS 45 and GPS 40? -What are the differences between the GPS 45XL and GPS II? | -What is the accuracy of the Garmin GPS units? -How does the GPS 12XL averaging feature work? | -Performance in trees? | 4.00 GENERAL USE QUESTIONS: -Why can't I get an initial fix? -How can I improve the accuracy of a GPS unit with averaging? -Can I post-process data from the GPS? | -How accurate is velocity measurement? -How accurate is the clock? -What is the MOB function? -What is a waypoint? -Which map datum do I use? -How does the GPS calculate the local magnetic variation? -Why do I get the message "Need 2D Altitude"? | -How do I calculate the distance between 2 locations? | -When will Selective Availability (SA) be turned off? | -What will be the effect of the GPS rollover in the year 1999? | 5.00 SPECIFICATIONS/REPORTS: -GPS 45XL/45/40/38 specifications? -GPS 45/40? -GPS 45XL? -GPS 38? -GPS II? -GPS 12XL? | -GPS 89 (aero)? -GPS 90 (aero)? -GPS 120? -GPS 130? -GPS 135? -GPSMAP 175? -GPS 20/25/30/31/35 (remote only models)? -GPS 30/31 description? 6.00 DIFFERENTIAL GPS (DGPS): -What is Differential GPS? -Garmin's GBR 21 Differential Beacon Receiver and alternatives? -Garmin's GBR 21 Differential Beacon Receiver unit report? | 7.00 FIRMWARE (INTERNAL SOFTWARE): -90 knot speed limit? -GPS 45/40 firmware versions? -What are the undocumented modes for the GPS 45/40/38/90/89/120/II/12XL? -What are some undocumented modes for the GPS 75? -Why is internal temperature available? -VMG error? -Garmin NMEA 0183 data sentences? | 8.00 BATTERY/POWER: -How is power selected between the internal batteries and the external supply? -What voltages do the GPS 45 fuel gauge correspond to? -Current consumption of a GPS 45 at different external supply input voltages? -How does BatterySave mode work? -GPS 38 batteries too tight? | -Batteries? -Other battery/external power options? -How long is memory conserved without batteries? -Does the serial I/O consume much more power when it is enabled? -What is the minimum external supply voltage for the GPS 45/45XL? | -What is the external voltage range for the GPS 12XL | 9.00 SERIAL/POWER INTERFACE: -External serial/power connector alternatives? -How do I interface the GPS 45/40/38/II/12XL to an IBM-PC compatible computer? -Can I use one cable for both power and data at the same time? | -Can I power my GPS from the serial port on my laptop or PC? | -How do I interface the GPS 45/40/38/II/12XL to a Macintosh? 10.00 APPLICATION SOFTWARE: -What Macintosh software is available? -What other (non-PC, non-Mac) GPS software for Garmins is available? | -What MS-DOS/Win software is available specifically for Garmin GPS units? -What MS-DOS/Win software is available that communicates using NMEA 183 format? -Other MS-DOS software? -GPS www/ftp sites? | -Digital maps with lat/lon? 11.00 ANTENNAS: -What is the GPS 40/38/12XL internal antenna? -How is the GPS 45/90/89/II antenna internally constructed? -How well does the internal antenna work inside a car? -What are the remote antenna options? -GPS 45 antenna extension cables? -Can I make my own external antenna? -What is the Trimble OEM antenna? | -What is the loss for different coaxial cables? -What is the GPS 40/12XL antenna connector? 12.00 MISCELLANEOUS: -GPS mounting options? -Waterproofness? -Cases? -Garmin 45/40/38 wish list? -Can I use my GPS unit in a plane? -Internal electrical hardware? -Why is the GPS 45/40/38/90/89 firmware not in a socket? -Can I receive GPS signals through my house? -For how long will a particular track interval collect data? -Where can I purchase a unit? ====================================================================== QUESTIONS AND ANSWERS: ---------------------- 1.00 ABOUT THIS FAQ: --------------- -General FAQ info? Unofficial Garmin FAQ Copyright 1995, 1996, 1997 by Lane A. Holdcroft. Original contributors retain their copyright for all of their contributions. You may copy this in its entirety, but not for monetary benefit. If a portion of this document is quoted, please give the original author credit. Thanks to the many people who have contributed to this document! I tried to give credit to the original author at the end of each contribution. If an answer does not have an attribution, I usually answered it based on my recollection of the consensus of previous postings and/or my personal experience (or the contributor did not want credit). Sometimes I delete some quoted material for brevity, grammar, or accuracy. If I felt clarification within another person's quoted material would be beneficial, my comments should always be contained within the brackets "[" and "]". The Usenet newsgroup "sci.geo.satellite-nav" has a high proportion of questions dealing with the very popular Garmin GPS units. This should answer most of them. The newsgroup was originally intended to be oriented more towards professionals in the GPS business rather than recreational users that are more inclined to use the low cost Garmin GPS's. However, there is a lot of discussion about Garmin units. This FAQ is based on my experience with my Garmin GPS units and others' postings to the GPS newsgroup since the GPS 45 was first introduced about March 1994. I have had a GPS 45, 38, and 12XL. I have a particular interest in the electrical aspects of these units. | The latest version of this FAQ and some links to other sites can be found at my www or ftp sites (or Peter's site in the next section): http://www.eskimo.com/~klah/index.html or ftp://ftp.eskimo.com/u/k/klah/index.html or ftp to "ftp.eskimo.com", cd to "/u/k/klah" For more general information not specific to the Garmin units, read the general GPS FAQ maintained by Peter Bennett. He also has an excellent NMEA FAQ. They are both available on his ftp site which is the best single site on the web for information and software on low cost GPS's. I also send the latest version of this Garmin FAQ there. ftp://sundae.triumf.ca/pub/peter/index.html http:://vancouver-webpages.com/peter/index.html ftp://ftp-i2.informatik.rwth-aachen.de/pub/arnd/GPS/peter/index.html A fair amount of the information posted about the Garmin units in the GPS newsgroup is incorrect. I have spent a lot of time trying to make this document error free, but there is no guarantee to the accuracy of this information! Minor errors have been found in the past. When the term "GPS receiver" or "GPS unit" is used in this FAQ, this is meant to refer to the handheld unit that uses the Global Positioning System. Technically, the "receiver" is the radio portion of the handheld device only and the term "GPS" refers to the complete navigation system and not the unit itself. ---------------------------------------------------------------------- -FAQ revision history? Ver Date Major changes --- ---- ------------- 1.00 Aug 4, 1995 Initial release 1.01 Aug 7, 1995 Minor corrections 1.02 Aug 20, 1995 Added detailed speed limit info Added GPS 90 info Added more detailed list of specs Added Garmin accessory list 1.03 Aug 22, 1995 Minor corrections 1.04 Aug 29, 1995 Added Garmin 45/40 wish list Added section head numbers Added GPS 45 external current consumption Added FAQ revision history 1.05 Sep 18, 1995 Added info about "Diag mode" Added info about Accuracy Added info about Garmin differential receivers Added "|" indicating major changes in line or paragraph Reordered several sections Split out application software into its own heading Many minor corrections 1.06 Oct 10, 1995 Added section on coax cable losses Added section on CD-ROM map programs Added section on houses blocking signals Added GPS 40 mode from a GPS 45 Added GPS 30 info Expanded www/ftp sites considerably Expanded Garmin DGPS info Split application software into Garmin & NMEA 183 Split out intro into a separate section Minor corrections 1.07 April 23, 1996 Added sections on GPS 38 & 120 Added info on BatterySave mode Added info on memory backup Added Eagle Accunav info (Performance in trees) Added other PC software section Added more info on Macintosh software Added improving the accuracy section Expanded Garmin GPS models section Reduced the Garmin software price Updated Garmin's address and phone numbers Updated several E-mail addresses 1.08 July 22, 1996 Added sections on GPS 45XL, 89, 130, 175 Added section on velocity & magnetic variation Added section on remote only units Added initial fix info Added undocumented GPS 75 modes Added VMG error info Added NMEA 183 info 1.081 Aug 8, 1996 Fixed variation/declination nomenclature 1.082 Aug 30, 1996 Corrected serial port statement Fixed Eagle/Lowrance UTM info Updated APRS files location 1.10 Mar 25 1997 Added sections on GPS II, 12XL, 89, 175 Added report on GPS 21 Differential receiver Added info on GPS week rollover in 1999 Added info about the Trimble OEM antenna Added info on GPS 38 tight batteries Added info about when SA will end Added info on 45 external power minimum voltage Added Delorme Tripmate reference Added Auto Locate mode power up option Added --- to separate questions Added === to separate sections Updated serial port maximum voltage information Moved Garmin products to front Deleted old GPS 45 NMEA info Replaced Eagle/Trimble Info w/ GPS 12XL Moved DGPS to separate section 1.101 Mar 29 1997 Fixed index and section header inconsistencies Fixed some grammar errors PLEASE DELETE ALL PREVIOUS VERSIONS! | The "|" character is used to mark paragraphs or a line for significant changes in content from the previous version of the FAQ. ---------------------------------------------------------------------- -Suggestions for improvement? You can help improve this document by sending E-mail to me about errors or suggestions for improvement. It would be very useful if you could give your sources of information. Also, please include the version of the FAQ and the model number and firmware version of your GPS unit. There is often conflicting information and your detailed references are valuable for resolving those discrepancies. I receive lots of feedback but it takes time to process and verify all of the information. Because of the large volume of E-mail I receive, I can not always answer individual questions not pertaining to the FAQ. However, I do consider all suggestions. I read the newsgroup very regularly but occasionally I do miss something Garmin related. I am still reviewing the many suggestions and postings that I have received for inclusion in future versions. Please send CONSTRUCTIVE suggestions to Lane A. Holdcroft ====================================================================== 2.00 GARMIN PRODUCTS: ---------------- -Garmin GPS models? There could be some mistakes! List prices change often. Discounted prices can be variable and they only apply to some dealers in the US. OUTDOOR/MARINE PRODUCTS INTRO $US $US MODEL USE DATE SPEED LIMIT DISC LIST ----- --- ---- ----------- ----- ----- GPS II marine, hiking, cycling 11/96 90 knots $220 $309 | GPS 12XL 12 channel hiking handheld 01/97 999 knots $260 $386 | GPS 38 marine, hiking handheld 1996 90 knots $150 $300 GPS 40 marine, hiking handheld 09/94 90 knots $200 $425 GPS 45 marine, hiking handheld 04/94 90 knots $250 $495 GPS 45XL marine, hiking handheld 07/96 90 knots $290 $495 GPS 50 marine, old, replaced by GPS 75 <1992 90 knots NA NA GPS 65 marine mount, works like GPS 75 1992 90 knots $400 $665 GPS 75 marine, hiking handheld 1992? 90 knots $380 $825 GPS 80 military GPS 40 w/ 5-40V input 1995 999 knots? $650 $900 GPS 85 military GPS 75 999 knots? $700 $900 | GPS 120 marine mount 45 w/ big display 1995 90 knots $320 $463 GPSMAP 130 12 ch marine mount w/ map ~04/96 90 knots $700 $1082 GPSMAP 135 12 ch w/map&sonar(no transd) 1996 90 knots $1190 GPSCOM 170 12 ch marine GPS w/ VHF radio 1996 ? knots $1082 GPSMAP 175 12 ch mar/hik map handheld 1996 ?? knots $700 $1082 GPS100MRN marine handheld/portable 90 knots $1850 GBR21 DGPS beacon receiver n/a $500 $799 MAP 205 chartplotter, no GPS n/a $770 $1249 GPSMAP 210 chartplotter, B&W 90 knots $1000 $1655 GPSMAP 220 chartplotter, color 90 knots $1650 $2730 Notice that all of Garmin's marine units (except the GPS 12XL) have an artificially low speed limit. This speed limit did not start with the Garmin 45 as some have suggested. AVIATION PRODUCTS $US MODEL USE SPEED LIMIT LIST GPS 55 aviation (discontinued) 1992 ? knots NA GPS 89 aviation, cheaper GPS 90 07/96 999 knots $450 $499 GPS 90 aviation, similar to GPS 45 04/95 999 knots $650 $699 GPS 95 aviation (discontinued?) ? ~999 knots? NA GPS 95XL aviation (aero ver of GPS 75) ? ~999 knots? $1495 GPS 100 STD handheld/portable 999 $1795 GPS 100 PRT handheld/portable w/ dbase 999 $2095 GPS 100 AVD handheld/portable w/ mnt rack 999 $2495 GPS 150 panel mount, VFR 999 $2995 GPS 155 panel mount, IFR, n-p approach 999 $4995 GPS 165 DZUS rail mount version of GPS 155 999 $6495 GPS 190 GPS w/ VHF transceiver 1996 ? $1399 GPS 195 aviation version of GPS 130 1996 ? $1299 GNC 250 panel mount GPS/COMM 999 $3250 OEM/BOARDS/SENSORS [These units do not have displays. They are for remote use only.] $US MODEL USE SPEED LIMIT LIST GPS 20 MultiTrac8 sensor board (eval kit), 999 kts $499 $150 in quantity w/o antenna, $240 in quantity w/antenna GPS 25 PhaseTrac12 (eval kit), 12 channel sensor board (eval kit), 999 kts $599 $225 in quantity w/o antenna, $315 in quantity w/antenna [this has a parallel receiver] GPS 30 Integrated antenna/sensor board 999 $340 $499 (eval kit), $240 in quantity GPS 31 Marine mount version of GPS 30 999 $355 GPS 35 12 channel version of GPS 30 999 $599 (eval kit), $315 in quantity GIS/SURVEY PRODUCTS $US MODEL USE SPEED LIMIT LIST GPS SRVY II portable w/ datalogging capabl. 999 $2995 ---------------------------------------------------------------------- -Garmin accessories? Here is a list of most Garmin accessories: List prices as of Feb 1995: [THESE PRICES ARE OLD AND SOME OPTIONS HAVE BEEN DISCONTINUED. however, this is the most complete list of accessories I have seen] [NOTE: All GPS 40 options except for antennas work on GPS 38] | GPS40 part number Item description list price GA27 Low Profile [patch] remote ant w/8ft $160.00 [RG-174] cable MCX connector & magnetic & suction mount 010-10061-00 Trunk lip mount GA 26/27 18.95 010-10062-00 Flange mount GA 26/27 18.95 011-00152-00 Suction cup mount GA 26/27 18.95 011-00153-00 Magnetic antenna mount GA 26/27 25.00 320-00048-00 8 ft extension cable GA 27 40.00 4015 GPS 40 carry case 35.00 4040 GPS 40/45 Cross load cable(unit to unit) 50.00 [320-0040-00] 4041 GPS 40/45 PC Interface cable [DE-9 conn] 30.00 4042 GPS40 data cable 25.00 4050 GPS 40 cigarette lighter adapter 50.00 4514 GPS 40/45 PC Software and cable kit 150.00 4518 GPS 40/45 mounting bracket 45.00 GPS 45 GA 26 low profile [patch] remote ant w/magnetic & suction cup with 8 ft [RG-142?] cable 160.00 BNC conn 320-0049-00 8 ft extension cable for GA 26 40.00 GA 28 [Mast mount] remote marine [quad-helix] ant w/30 ft [RG-58] cable and BNC connector 160.00 010-10067-00 GA 28 flange mount kit 22.00 1011 Marine/RV remote ant w/30 ft cable BNC 160.00 [discontinued?] 1013 30 ft low-loss ant ext cable w/connectors 115.00 1028 Magnetic mount ant with 10 ft cable 160.00 [discontinued?] 4522 GPS 45 handheld/portable ant 100.00 GPS 45-000 GPS 45 w/ Portable? antenna 495.00 [GPS 45-100 GPS 45 w/ GA28 antenna] [GPS 45-200 GPS 45 w/ GA26 antenna] 5519 Remote antenna mount: suction cup/screw mount w/ 6ft cable BNC 40.00 4040 GPS 40/45 Crossload cable (unit to unit) 50.00 4041 GPS 40/45 PC interface cable 30.00 4514 GPS 40/45 PCX5 Software and cable kit [now 100.00] [010-10054-00] 4515 GPS 45 carrying case 35.00 4518 GPS 45 mounting bracket 45.00 [010-10048-00] 4520 GPS 45 power/data cable 30.00 [010-10082-00] 4550 GPS 45 cigarette lighter adapter 25.00 [010-10085-00] Disclaimer: These prices may not be current list check around and see if deals exist Sid ( a buyer not a dealer, stockholder and have no vested interest in Garmin) ====================================================================== 3.00 GENERAL GARMIN QUESTIONS: ------------------------- -What are some key features of the Garmin GPS 45/40/38/II? Relatively inexpensive (list < $500 US, discounted < $150 US for GPS 38). Very easy to use. | Very feature rich. Battery life is over 10 hours w/ 4 AA alkaline batteries. Very compact size. Serial port allowing transfer of data to/from a PC/Mac. Neat 768 point track log feature which can be graphically displayed. Ability to download the above track log data to a PC/Mac. Easy to use due to a simple menu system. Some water resistance. | 64 x 100 pixel graphical display. Over 100 mapping datums used around the world. ---------------------------------------------------------------------- -What are the disadvantages of the GPS 45/40/38/II? 1) There is a firmware speed limit of 90 knots / 104 MPH. See "90 knot speed limit" question elsewhere in the FAQ for more details. The GPS 90/89/12XL do NOT have this limitation. 2) The list prices on some options are more expensive than some competitors. For example, a replacement 45 antenna is $100 list. However, some dealers offer substantial discounts. 3) Because of the GPS 45/40/38/90/89's compact size, there is not sufficient space for number buttons. It has a 4 position rocking button to enter numbers and labels like the high score on a video game. This is not as fast as using a keypad. 4) The display size is small. This is a very compact GPS unit. The character size is also very small on the GPS 45/40. However the the newer units use a slightly wider font to be more readable. If you have good corrected vision, it should not be a problem up close. | 5) The GPS 45/40/38 (like all other single channel sequential receiver GPS units) are not able to track as well under heavy tree cover as parallel receiver designs. However, this limitation can be overcome with an amplified external antenna. See "Performance in trees" section for details. | ---------------------------------------------------------------------- -Comparison of the GPS 38/40/45/45XL/II/89/90/12XL? | You can understand the Garmin product family a lot better if you realize that they have a few basic design features. | Garmin basically makes 2 GPS engines: | MultiTrac8: 1 parallel channel that sequences through 8 satellites 12 channel: True 12 channel parallel design Garmin basically makes 2 input power circuits: | 10-40V input, 12-14V is most ideal (GPS 45/II/12XL/90/89) 5-8V input, 8V is most ideal (GPS 40/38) Garmin basically makes 2 different included antennas: | Swivel quad-helix (GPS 45/II/89/90) Internal patch antenna (GPS 40/38/12XL/175/195) Note that all of the following units (except the GPS II) have a very similar case except for the antenna and external antenna connectors. Also note that all except the 12XL use the same MultiTrac8 engine. GPS 38 40 45 45XL II 89 90 12XL Pri Use Marine Marine Marine Marine Bik/Hik Aero Aero Hiking Channels 8/1 8/1 8/1 8/1 8/1 8/1 8/1 12 Case style 40 40 45 45 Triang 45 45 40 Antenna Intern Intern Extern Extern Extern Extern Extern Intern Ext Ant Conn. None MCX BNC BNC BNC BNC BNC MCX Max Ext V 8V 8V 40V 40V 36V 40V 40V 40V Beeper No Yes Yes Yes No Yes Yes Yes Newer firmware Yes No No Yes Yes No No Yes Speed limit(kt) 90 90 90 90 90 999 999 999 Aero Nav Info No No No No No Some All No Yoke mount No No No No No No Yes No Ant. ext. cable No No No No No Yes Yes No ~Retail $ $300 $425 $500 $500 $450? $600? $800? $500 ~Discount $ $150 $200 $250 $290 $220 $450 $650 $260 [info is not guaranteed!] ---------------------------------------------------------------------- -What are the differences between the GPS 45 and GPS 40? 1) ANTENNA: The GPS 45 has an external quad-helix swivel antenna (about 3/4" x 3/4" x 3") whereas the 40/38 has compact "patch" antenna built into the main case. A GPS 40/38 looks like a GPS 45 without the swivel antenna. The GPS 45 uses a standard BNC connector for the antenna, whereas the GPS 40 has a "MCX" type connector for the optional external antenna and the GPS 38 has no external antenna connector. The GPS 45's external antenna hangs out the side of the instrument and could be broken if it were snagged or handled roughly ($100 replacement cost!). This is not a problem with the GPS 40/38. The GPS 45's BNC connector is preferable if you want to add an extension cable since BNC extensions are available from many more sources. This is an advantage because you can avoid the cost of an additional antenna if you want to temporarily mount it remotely from the GPS unit. The GPS 45's BNC connectors are more susceptible to corrosion from salt water and the 45's antenna could leak if it was not well sealed. Many weren't. The GPS 45 can be held at different viewing angles as long as the antenna is swivelled vertically whereas the GPS 40/38 must be held at a specific angle for optimum reception. There is a lot of debate about the exact differences in antenna sensitivity. I could not see a difference in side by side tests. However some people feel the GPS 45 is slightly more sensitive particularly when the unit is first turned on. | 2) The GPS 45 takes a much wider range of input voltages (up to 40 Volts). This is because the 45 has an internal switching power supply whereas the GPS 40/38 do not. The GPS 40/38 are only rated for 5 to 8 Volts for external power. Connecting the GPS 40/38 directly to a higher voltage supply could be potentially damaging. Therefore, the mobile power cigarette adapter is about $20 more expensive for the GPS 40/38 (because it must include a regulator). Also, the GPS 40/38 has an additional center pin in the center of the power/data connector to prevent the use of the GPS 45 cigarette lighter cord which would probably damage the GPS 40/38 due to overvoltage. 3) The GPS 40/38 has a dark gray case, whereas the GPS 45 has a white front case and a black rear case. 4) They are priced differently. | ---------------------------------------------------------------------- -What are the differences between the GPS 45XL and GPS II? | Here is a summary from Steve Kanavos: My Garmin GPS II just arrived today. What a nice unit. The software is no comparison to my 45XL's. Here are some differences just for the curious ones until I post a more detailed review. What's New compared to 45XL 1. Horizontal or Vertical Display 2. 3 Stage backlighting 3. Supposed longer battery life ..15 hrs normal 4. Much more solid construction. 5. 106 Datums Plus User definable! 6. Better display (at least I think so) 7. Improved Ant mounting and performance (had my 45XL side by side) 8. Two additional zoom buttons 9. User selectable displays of Max Speed, Ave Speed, Total trip time and more. 10.Easier menu navigation 11.Lower price! I will provide more detail later on. What's missing compared to the 45XL 1. No warning sounds 2. No carrying case 3. Not dry nitrogen filled or laser welded case however it is well gasketed throughout. (Unit can be opened as it is a two piece design. 4. Green versus black LCD SOME COMMON STUFF 1. Computer interfaceable 2. Uses standard BNC Antenna connection as well as provides +5 Volts to the BNC connector. 3. Power 5-36 Volts 4. The GPS II maintains the software capabilities of the 45XL as well. "Steve J. Kanavos" ---------------------------------------------------------------------- -What is the accuracy of Garmin GPS units? Note that the error tolerance displayed on the GPS does not include errors due to SA and that all position accuracy specs for the GPS are based on 95% DDRMS and ASSUME EXCELLENT SATELLITE COVERAGE. This will not be the case if you are surrounded by buildings, hills, or thick trees! Horizontal accuracy: 100 meters Official accuracy (Selective Availability ON) <50 meters Actual current accuracy (Selective Availability ON) 15 meters Theoretical accuracy (Selective Availability OFF) 5-10 meters Differential accuracy (regardless of Selective Availability) Vertical accuracy (altitude): Approximately 1.6 times worse than horizontal accuracy depending on the geometry of acquired satellites. In fact, you can get much better vertical accuracy with an altimeter (but it must be regularly adjusted to compensate for changes in barometric pressure). The variations in altitude due to SA are especially obvious when you are on the ocean! Another possible source of error on some (apparently non-Garmin) GPS units is that GPS altitude is the height above the selected mapping datum reference, not height above mean sea level. | However, apparently the Garmin units can calculate the difference between mean sea level and the datum and correct for that in the displayed altitude. This is based on my observations of the NMEA data from my GPS 45 and the NMEA FAQ. This data is available in the NMEA 183 V2.0 sentence "GGA". | ---------------------------------------------------------------------- -How does the GPS 12XL averaging feature work? | It seems to work pretty well. To activate it, you must first press the "MARK" button and select "AVERAGE" from the menu. You are supposed to be stationary. You can see the estimated error drop the longer you leave it in this mode. You can save the averaged waypoint. The error estimate does not appear to include Selective Availability. | ---------------------------------------------------------------------- -Performance in trees? GPS reception is always difficult in thick trees for all GPS receivers. The attenuation depends on the density of the canopy, and how much moisture is in and on the leaves. If the canopy is too dense, you may have to find a clearing to get a fix. I have observed that the Garmin sequencing receivers using the included antenna perform well among trees that grow in very dry climates but perform poorly among trees that grow in wet climates. | Several other people have reported that the external antennas work better than the built in antennas when they are walking through trees. This is because most external antennas are amplified and your body is not shielding the signal. If you are walking, you could mount the external antenna to your hat or to a pipe coming out of a backpack. | The GPS 45/40/38/II do not perform quite as well as some other units when surrounded by trees. It was believed that this is because the GPS 45/40/38/II has a single channel receiver that sequences between 8 satellites instead of having more continuous channels like many other units. Parallel receivers are able to track more marginal signals at once. However, they cost more and do not have the battery life of a sequencing receiver such as the GPS 45/40/38/II. The performance of my GPS 45 and a friends 12 channel GPS 35 (with a built-in antenna) were compared side by side as we drove through a heavily wooded park. (We actually compared the HDOP's and number of satellites tracked.) The GPS 45 was inferior with its built in antenna. | However, when the test was repeated and I used an amplified remote antenna on my GPS 45, the performance was very comparable with the 12 channel GPS 35! | Therefore, I now believe that additional antenna amplification for the GPS 45 is more needed than a having more parallel channels! | Garmin just started shipping the GPS 12XL which is a new 12 channel handheld instrument in a GPS 40/38 type case. It does perform better under trees than my GPS 45 but I have not done a controlled test yet. | ====================================================================== 4.00 GENERAL USE QUESTIONS: --------------------- -Why can't I get an initial fix? The "initial fix" occurs if the GPS unit has moved more than several hundred miles (which is also usually the case when you first receive a new GPS unit). This is a very common problem for new GPS users. It is useful for technical reasons for the GPS unit to know approximately where the satellites are relative to the GPS unit so that it can get a fix more quickly. Also, if the unit has not been used in quite a while (more than a couple of weeks), then the satellite orbital info will not be up to date. It takes about 12-30?? minutes to update the satellite orbital almanac (long term, less accurate) and ephemeris (short term, more accurate) data. | These tips are also useful even if you have had the unit on recently. | Here is a very conservative approach to getting a quick fix on any GPS: 1) Find a location with a VERY clear view of the sky not blocked by buildings, trees, etc. 2) Preset your approximate location to really speed up the process. The new GPS 45XL/38/II/12XL have added a quick start location feature to the firmware which asks you your approximate location. It goes into this mode if it can't find the satellites quickly. Of course the GPS can calculate where it is on its own, it just takes longer. 3) Put the unit in Operation Normal (or sky search if you don't know your location from a map), not BatterySave mode (this mode seems to be less aggressive in finding weak signals). 4) Make sure your antenna is properly angled. On a GPS 45/II, the antenna should be vertical. On a GPS 38/40/12XL, the unit should be held level, so the display faces up. 5) Go to the satellite screen and watch the signal strength bars appear. (If you have a GPS 45/40, I would use diagnostic mode so you can see the hollow vs. solid bars. This is documented in the FAQ under the FIRMWARE section). 6) Allow lots of time for your unit to acquire a fix. It could take a long time if you don't have a good view of the sky. I wouldn't totally give up on it until you have given it over an hour. If you do not have a clear view of the sky, or the satellites are not in optimum positions, or you the GPS unit needs to download the latest satellite orbit corrections, it would be helpful to have the extra time. 7) If you still don't have a fix after several hours and you REALLY had a clear view of the sky, your GPS receiver may be broken. You might try a new set of batteries just in case. In general when you are having trouble getting a fast fix (not the initial fix that we have been discussing here), turning the unit off and then back on can allow you to get a much faster fix. (This is mentioned in the manual). I use this trick all of the time and it helps substantially! Also, it seems to take longer to get a fix when you are moving fast as in a car or fast boat. ---------------------------------------------------------------------- -How can I improve the accuracy of a GPS unit with averaging? Although the official accuracy of the GPS system for non-military users is 100 meters 95% of the time, in fact when you look at the data plots (such as available from MIT in the www/ftp sites section), you can see that the accuracy is much better than 50 meters 95% of the time if you are stationary. One credible poster collected some data suggesting that when you are moving at about 60 MPH, the accuracy is closer to 70 meters (about twice the stationary error) 95% of the time with most common non-surveying GPS units. Accuracy can be improved much further by averaging. You can turn on the track log feature and select a timer interval, then leave the GPS on for a long time, and then look at the map screen and then just visually average the position. Of course this can be done more precisely by downloading the track log data and averaging it on a computer. [Lane Holdcroft] I have made some simple tests of SA errors and found that they seem to be random (and therefore, by definition, unpredictable) with a temporal autocorrelation function that drops to about 0.3 in 15 minutes. Thus, it is of very little advantage to take readings at intervals of less than 15 minutes. For readings [evenly spaced] separated by 15 minutes or longer, the error of the mean drops as the square root of n. (Robert S. Lawrence) The above conclusions were drawn from averaging days of data. If you are only averaging several hours of data (or less), then it would be beneficial to take readings much more often (such as every minute) so that you can get a significant number of data points. | The concept of averaging is based on the assumption that the errors (especially due to SA) are centered around zero. In fact the specification for SA does not require zero offset, but this is usually the case. Many people feel that accuracy within several meters is achievable. This looks very reasonable looking at the MIT plots. | ---------------------------------------------------------------------- -Can I post-process data from my GPS? | Post-processing is a way of applying differential corrections after the waypoints are saved. Because the non-surveying units do not save the individual satellites used and their timing information for each fix, you can NOT accurately post-process the data. Your accuracy will probably only be about 20 meters. Another problem is that the displayed information is averaged using a temporal filter rather than being real-time. This averaging is detrimental when you are trying to post-process the data. Yet another possible problem is that if more than 4 satellites are used in the position calculation, the weighting formula for the satellites may not be known. | ---------------------------------------------------------------------- -How accurate is velocity measurement? With the Differential GPS option, velocity accuracy should be very good, otherwise it is generally poor. Because of Selective Availability, velocity at very low speeds is almost worthless. I have seen speeds up to about 3 knots when I was stationary and had good satellite reception. This error becomes smaller (on a percentage basis) as your speed increases. To get really accurate velocity without using Differential GPS, you usually need to have a very expensive (usually surveying grade) receiver with some very sophisticated software that monitors the phase of the military frequency. Therefore, virtually all handhelds that are less than about $1500 are not very accurate for velocity without DGPS. Probably to prevent the wanderings of SA, the Garmin 45/40/38 will display "0.0" (without the DGPS option) if the speed is less than: 1.0 knot 1.2 statute miles/hr 1.8 kilometers/hr Also, compass headings do not appear to update unless you are going at least twice the above listed speeds (presumably to keep the compass headings from being meaningless at such low speeds)! When you are moving very slowly (such as hiking), obviously it would be preferable to use the "North Up" option for the map to prevent the map orientation from jumping around in circles. | ---------------------------------------------------------------------- -How accurate is the clock? First of all, there is a clock IC in the unit to keep the approximate time when the unit is not locked on satellites. To get accurate GPS time, you must be locked on satellites. Internally the GPS unit calculates the time more accurately than 1 uS, however the display and particularly the serial port are lower priority tasks and will not be updated immediately. We do not know the maximum error. When I have crudely compared the displayed time to the international time standards (received by shortwave radio), the difference usually seems to be well under one second (but there are no guarantees). To get accuracy of around 1uS, Garmin and other manufacturers make boards that have a 1uS or better precise timing output. Also, Tom Clark has designed a "Totally Accurate Clock" that is based on several models of GPS and greatly increases the time accuracy through averaging. See the www/ftp sites section for the address. | ---------------------------------------------------------------------- -What is the MOB function? The "Man Over Board" function is a common feature for marine GPS units. If a person were to fall overboard, the skipper uses this function to immediately mark the current location and the GPS goes into a "Go To" mode where it directs the skipper back to the point where the button was pressed. It is difficult to find a person at sea with large waves. ---------------------------------------------------------------------- -What is a waypoint? A waypoint is a nautical term referring to a label used to mark a specific location. For a GPS unit, a waypoint can be any location you want to mark and label in memory for future reference. ---------------------------------------------------------------------- -Which map datum do I use? A map datum is a mathematical model of the earth's shape and it specifies how a grid should be placed on it. The earth is not a true sphere, but an ellipsoid. The datum describes the radius and eccentricity of the ellipsoid as well as the offset of the grid. The Garmin units have over 100 mapping datums used throughout the world! The key point is to use the same datum setting in your GPS as is used on your map or you could easily be off by hundreds of meters. Here are the most commonly used datums in the US: WGS84 WGS-84 is considered a very accurate simple worldwide datum. Most maps in the US are moving towards WGS84. Most CD-ROM maps use WGS-84. NAD83 is almost identical to WGS-84 with differences of only a few millimeters. NAD27 CONUS Used by most current U.S. Forest Service and USGS maps. The CON represents Continental or Contiguous US. | There are many other NAD27 versions for North and Central America such as NAD27 CANADA ---------------------------------------------------------------------- -How does the GPS calculate the local magnetic variation? | The GPS unit has a formula programmed into the firmware that predicts the magnetic variation for a particular location on the earth. Apparently mariners use the term variation and landlubbers use the term declination. Of course there could be other local magnetic disturbances, so check your charts. | ---------------------------------------------------------------------- -Why do I get the message "Need 2D Altitude"? | To get a 3-Dimensional fix (horizontal, vertical, and altitude), you need 4 satellites (time is the 4th variable for those mathematically inclined). If your GPS unit can only use 3 satellites, then you may be prompted to enter the altitude (on the position screen) so that it can get a precise fix. On the rare occasions that I get that error, I make sure that I have a good view of the sky and then turn off the power and turn it back on and I usually get a 3-D fix. | ---------------------------------------------------------------------- -How do I calculate the distance between 2 locations? | I will put a couple of approximate formulas here in the future. I need to doublecheck them first! There are so many with so many different levels of complexity and accuracy. For a very accurate free PC program that does the calculations, see victorf's site in the www/ftp sites section. The files are INVERSE.ZIP and DIRECT.ZIP There is also a FAQ file at Peter Bennett's ftp site that has some info. For much more detail about the calculations, see the hang gliding FAQ. It has a very detailed section on distance calculations. ---------------------------------------------------------------------- -When will Selective Availability (SA) be turned off? | Selective Availability is the deliberate program of adding error to the GPS positions through the manipulation of the signal timing on the satellites. This is done for the US military to discourage their use on missles by enemies. The US military has special receivers that can decode the full accuracy of the available signal. Some people think that these codes could be easily cracked. Anybody that thinks that does not understand the complexity of the problem. It was developed by Cryptologists to prevent other Cryptologists from breaking it. Unfortunately, it is very secure. | It is true that SA was turned off during the Persian Gulf War and the invasion of Haiti. This was only because there was a shortage of military GPS receivers and the US defense department bought some non-defense ones. Although the enemy had the benefit of non-SA accuracy, they had very few GPS receivers compared to the number that the US could use. In 1996, the US Government issued a formal statement that SA will be in affect for at least the year 2000 and up to 2006. They will make the determination whether to extend SA after the year 2000. Of course the US government can change the postion at any time in the future. The official US Government statement is at the site http://www.navcen.uscg.mil/ | Remember, the GPS signals were only originally intended for the US military and they don't charge anyone to use them! It is the US taxpayers that are actually paying for the system. If fact the US Government is NOT degrading the signal to the full 100 meters (95% of the time) but is actually running at about 35 meters. | ---------------------------------------------------------------------- -What will be the effect of the GPS rollover in the year 1999? | For the GPS to help keep track of time, the satellites broadcast the "GPS week". GPS week zero started Jan 6, 1980 but the GPS week is limited to a maximum number of only 1024 (10 bits). Therefore at midnight between Aug 21 and Aug 22 1999 UTC, the GPS week will roll over to zero which may be interpreted as Jan 6, 1980. If the software engineers did not anticipate this, then the time would be screwed up in the GPS. Apparently MAGELLAN (NOT Garmin) issued a press release stating that some of their older units need to have a free firmware upgrade. However, Garmin has stated in writing to me that they did foresee this problem and they say that all Garmin units should be unaffected by the GPS week roll over. Also one of the founders of Garmin was quoted in a magazine as saying the same thing. | ====================================================================== 5.00 SPECIFICATIONS/REPORTS: ---------------------- -GPS 45XL/45/40/38 specifications? Here are the specs out of the manual: Physical -------- Case: Ultrasonically welded, dry nitrogen-filled | Size: 6.15"H x 2"W x 1.23"D (15.6 x 5.1 x [3.1] cm) Weight: [9 ounces, 255g] w/ batteries. Temp Range: 5 to 158 degrees F [-15 to +70 degrees C] Performance ----------- Receiver: Differential-ready MultiTrac8 Acquisition Time: Approx 20 seconds (warm) Approx 2 minutes (cold) Approx 7.5 minutes (autolocate) Update rate: 1/sec, continuous Position Accuracy 5-10 meters (16-33 ft) with DGPS correction 15 meters (49 ft) RMS* (note: I average 150') *subject to accuracy degradation to 100m [95% of the time] under the DOD imposed Selective Availability Program Velocity Accuracy 0.1 knot RMS steady state [w/o SA, several knots error w/ SA] Dynamics: Performs to specs to 3g's [Navigation Features -------------------- Waypoints: 250 alphanumeric Routes: 20 with 30 waypoints each] | Power ----- Input: 4 AA batteries or [GPS 45/12XL 10-40 VDC | GPS 40/38 5-8 VDC] | Usage: .75 watts Battery life: 10 hours (normal mode) w/alk. batt. Up to 20 hours in battery saver mode Kai Schumann ---------------------------------------------------------------------- -GPS 45/40? Here are 2 good reviews that were posted to the newsgroup. One is from a 45 (not the software enhanced 45XL) owner, the other from a 40 owner. Keep in mind that other than the antenna and input voltage range (and software enhancements), both units are very similar and most comments apply to both. | I have included their reviews pretty much in full because they do a very good job of covering the features of these units, and they both include lots of useful information which would be beneficial to someone who is contemplating buying a Garmin unit. >From: (Gavin Scott) Date: Wed, 27 Apr 1994 04:46:39 GMT Today I received a new Garmin GPS 45 Here are my initial impressions, along with a list of features and specifications for the unit. I will follow up with more comments in a week or so after I have had a real chance to play with it for a while. I have no connection with Garmin or West Marine. I purchased the GPS 45 myself, for my own use. I have owned handheld GPS receivers going back to the original Magellan Nav-1000 (which has now been upgraded repeatedly and is a NAV5000 now). I have some experience with other GPS units including a Garmin GPS100 owned by a friend. The brand new (shipping for only a week or so) Garmin GPS 45 looks to be the hottest handheld around. It is a small (literally pocket sized) 10oz package, and yet sports a large graphic LCD display. For a picture, look in the current West Marine catalog (you can get one from them at 1-800-538-0775) or most other marine equipment dealer catalogs, or call Garmin at 1-800-800-1020 and ask them to fax you a data sheet. ------- GARMIN GPS 45 --------- PHYSICAL DESCRIPTION: This sucker is small! It easily disappears into the front pockets of my Levis Dockers. The spec sheet lists the dimensions as 6.15 inches high, 2 inches wide, and 1.23 inches deep. Weight is an amazing 10 ounces (spec sheet, 4 AA batteries included), and my cheap postal scale weighs it in at 11 ounces (with batteries and case). At the top on the right side is a recessed BNC connector where the tiny built in flip-up antenna is attached. The antenna is of the same sort as the Magellan and Garmin units have used for some time, except for the size! The GPS 45 antenna measures 3 inches long by 0.775 inches square. The dimensions of the main unit given above do not include antenna, which makes the top of the unit about 3 inches wide overall. The most striking feature of the GPS 45 (after size) is the large LCD display which takes up the bottom half of the front of the unit. The display has a 'portrait' orientation, being much taller than it is wide. Above the display is a four way rocker switch surrounded by six other buttons. This layout allows the unit to be easily held in either hand with the thumb operating the buttons. The joystick like flat rubber rocker switch is used for all data entry. Alpha-numeric data is entered by cycling through the possible letters/numbers. To the left of the rocker 'cursor' button are (top to bottom) GOTO, Power/Backlight, and QUIT buttons. to the right are PAGE, MARK and ENTER. The top 1/4 of the front is blank except for a logo (picture of the earth with no text). The front part of the unit is white, and the back is black. Batteries (4 AA) are inserted into the bottom, beneath a seal opened with a quarter turn fold out doohickey. The batteries disappear into two tubes. I don't know where they have room for the electronics with all that space taken up inside by the batteries! A 4 pin (round DIN like) connector is on the back. The pins are described in the manual as Ground, Power in ([10]-40 VDC!), and DATA IN and DATA OUT. A rubber plug protects the connector when it is not in use. The whole unit is waterproof, and is actually filled with dry nitrogen and the waterproofness is covered by the one year warranty. ACCESSORIES INCLUDED: 4 AA [alkaline] batteries (installed). [A carrying case.] A reference manual (61 pages, dated February 1994). A quick reference card (which is too big to fit in the case, but printed on plastic waterproof paper). Warranty registration card. An offer to sell you a training video for $29.95 A wrist strap. The whole mess comes in a white cardboard box with pale Garmin logos on it that is about 11"x7"x3". SPECIFICATIONS: Temp range 5-158 degrees F (-15-70C). Acquisition times: 20 seconds (warm), 2 minutes (cold), 7.5 minutes (sky search). Update rate 1/second. Position accuracy 5-10M (with DGPS), 15M RMS (without SA), [100 Meter accuracy with 95% confidence (with SA on, as is the case now)] Dynamics: 3g's. Power usage .75 watts. Battery life 10 Hours normal, 20 hours battery saver mode. NMEA INTERFACE INFORMATION: NMEA 0180, 0182. [GPS 45/40 info:] 0183 version 1.5 (Approved sentences BWC, GLL, RMB, RMC, XTE, VTG, WPL; Proprietary sentences PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control)). 0183 version 2.0 (Approved sentences [GGA], GLL, GSA, GSV, RMB, RMC, RTE, WPL; Proprietary sentences PGRME (estimated error), PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control). [For the GPS 38 and 45XL, the following sentences were added: NMEA 0183 V1.5 BOD NMEA 0183 V2.0 WPL and PSLIB] | Plus Garmin's proprietary bi-directional format that allows upload/download of waypoints and other information with appropriate software. DGPS corrections are accepted from any RTCM-104 v2.0 format compatible beacon receiver, but use of Garmin's GBR 21 (discounted to $500) will allow tuning and control from the GPS 45 itself (using the proprietary NMEA data strings above). OPERATIONAL DESCRIPTION, FEATURES, PRELIMINARY EXPERIENCES: To turn it on, you press the power button down firmly. You are greeted with an animated spinning globe and in large letters "Welcome to the Garmin GPS 45" and it gives the firmware revision as "2.02". First displayed is the satellite status screen. This nifty display shows the position in the sky for each satellite, a bar graph of the signal strength of up to 8 stats at a time, a large battery power gauge bar, a backlight indicator (a very useful feature in daylight when you can't tell if the blue EL backlight is on or not), and a status message ("Acquiring" etc). Pressing the PAGE key cycles through the main displays which are as follows: POSITION PAGE: Shows a graphical compass display (like looking at a compass from eye level). Ground track and speed, Position in LAT/LON down to .001 minutes resolution, Altitude (including an accuracy +- value!), and the current time (Local time not GPS time) with 1 second resolution. MAP SCREEN This is way cool. You get a moving map display that will let you zoom from a 0.2 mile range up to 320 miles. You can also pan around, point to waypoints, create new waypoints by pointing etc. There is no provision for a map database, but the nine nearest waypoints can be displayed with their names, along with range circles, course, ground track, and other information, all configurable. You can have TRACK UP or NORTH UP as you like. CROSS TRACK (CDI) SCREEN: Shows bearing and distance to next waypoint, graphical XTE and distance to go, current time and ETE, Track and Speed, etc. MENU SCREEN: >From here you get to enter waypoints and routes and do all the setup stuff. There are about 16 screens of config data and stuff accessible. OTHER MISCELLANEOUS STUFF: Let's see, it is getting late so let me try and highlight the other unusual features. Of course all the stuff for creating routes and waypoints is there. You get 250 Alphanumeric waypoints (which you can add an annotation line of info to!), 20 reversible routes, Man Overboard mode (Press GOTO twice). I have only operated it outside enough to get an initial fix (sky search) and try out some basic stuff and the moving map. If you lose memory (almanac) data or move >300 miles you are forced to do a 7.5-15 minute sky search [unless you enter the new coordinates]. Once this is done, acquisitions are fast, multiple satellite tracking is quick, and overall the thing seems to work wonderfully. All the usual config options are there (Statute, Nautical, or Metric units, True, Auto magnetic, or Manual magnetic headings). There are 102 different map datums in the system (including some really off the wall stuff), but no option to enter your own (but yours is probably already in there). Positions can be displayed in DDDMM.MMM or DDMMSS.S format or UTM coordinates, or British, Irish, or Swiss GRID formats. CDI scale can be +-.25, 1.25 or 5 Miles or kilometers. You can choose to display CMG/VMG rather than track/speed. There is a simulator mode [which simulates strong satellite reception so you can practice operation of the unit indoors]. The differences between normal and battery saver mode are not described (other than to say that battery save mode saves 50% of the battery power and is "suitable for most applications". Velocity is allegedly limited to about [104] MPH, but there is no mention in the manual about it. Well, that's all for now. There are a number of other minor features but this should give you an idea. Overall, this is one of the niftiest gadgets I have ever seen, and definitely the best handheld GPS I have seen yet! Gavin Scott ------------------- >From: (Steve West) Subject: Garmin GPS 40 features summary Date: 14 Sep 1994 15:59:26 GMT Here is a brief review of Garmin 40 features. I'm just a novice. Also, this is just a skim of the features. The unit provides all kinds of shortcut ways to do things. I have also missed several features in this review. The unit comes with a 60 page manual. It still has references to marine stuff, but for the most part, it provides general descriptions/instructions applicable to land or water use. ... STATUS AND POSITION PAGE: This page has a polar plot of satellites that are visible over your horizon. The display is "live" so the positions of the satellites change with time. They are represented by numbers. Below the polar plot is a space for 8 signal strength bar graphs. As a satellite is acquired, the number on the polar plot is changed from inverse to normal video, and a bar graph for the satellite strength is created. The bar graphs are shuffled as new satellites are acquired, or old ones move out of view, or the "lock" was lost. 3 satellites are required for lat/long and 4 to add altitude. It also estimates the horizontal accuracy of the result [based on the geometry of the acquired satellite locations]. It usually states an accuracy between 500 ft and 49 ft. Once the unit is set up for your location, it can usually acquire 5-7 satellites within a couple minutes after turn-on. It seems pretty insensitive to orientation. If it cannot maintain a lock on at least 3 satellites, it sends you an alarm saying poor GPS coverage. POSITION PAGE: The position page shows your current lat/long/altitude. There is a moving compass segment at the top that shows your current bearing if you are moving. It estimates your velocity too, and shows you the current time. NAVIGATION PAGE: This page shows an active course deviation indicator (CDI). It allows you to choose a waypoint target, and then you simply follow the roadway to your destination--this is really cool! It estimates your velocity and arrival time and a bunch of other things. It also provides a Man Overboard function (MOB). MAP PAGE: The map page plots a map of waypoints and your current course. You can zoom and pan the map. The waypoints are indicated with a square and the name you gave them as you input them. At any time, you can simply highlight a waypoint on the map and it will tell you the required bearing and distance to get to it. It does lots of other stuff too. MENU PAGE: This page allows selection of 11 menu systems: 1. Nearest waypoint list (shows 9 nearest waypoints). 2. Waypoint list (lists all waypoints and allows you to look at them in detail) 3. Waypoint (details of single waypoint) 4. routes (allows development of up to 20 routes with 30 waypoints each along with editing, copying, pasting etc. You can also specify preferences for waypoint summaries to show DTK, ETE, ETA, etc). 5. Distance and sun calculations (allows input of 2 waypoints for distance and bearing calculation and shows sunrise/sunset times at the destination waypoint). 6. Operation menu (allows selection of unit mode, time offset, LCD display contrast, backlight time, and tone/beep control). 7. Navigation setup (set up position display format, map datum format, CDI scale, units preference, magnetic headings). 8. Track and log setup (allows the unit to automatically make a log of your positions. You can set it up for time or distance intervals for auto data taking plus a bunch of other stuff). 9. Map setup. configure the map display with polar rings, show route or not, show names or not, select preference north up or track up etc, configure track log plotting). 10. I/O setup (configure I/O and differential GPS). 11. messages menu (whenever the unit sends you an alarm for one reason or another, it details the message here). MARKING WAYPOINTS: Marking waypoints is as easy as pressing the mark button. The current lat/long/time are stored. You can give the point a name and provide your own comments and put the point in a specific route number if desired. APPENDICES [from manual]: A. Glossary of terms B. Messages possible on message page. C. Longitudinal time offsets [in hours] D. Map Datums E. Maintenance and Specs. F. Electrical wiring and interfaces. G. Installation of optional mounting bracket and I/O connector. H. Index Steve West ---------------------------------------------------------------------- -GPS 45XL? The GPS 45XL is simply a GPS 45 with the improved GPS 38 firmware. The GPS 45XL started shipping in July 1996. To see what additional software features were added, see the GPS 38 section below. Because the GPS 45XL has a few more features than the existing GPS 45, the GPS 45 has been discounted and is being phased out. ---------------------------------------------------------------------- -GPS 38? The GPS 38 was released late Feb 1996. Also see the comparison chart at the beginning of the FAQ. Here is some info from Garmin's press release: The GPS 38 [software] is similar to the GPS 40, but with the following improvements: A significantly lower price. "EZinit" for quick and easy first-time initialization. Users simply select their country, state or province for a fast, first position fix. "Backtrack" - an extension of the route feature that allows users to exactly re-trace their course based on their track log history, without having to manually create waypoints along the way. "Compass navigation" - a new page that graphically depicts a rotating compass dial. A large, directional arrow shows your bearing to your destination. "Re-designed moving map" - allows a larger presentation of information pertinent to the particular trip. "Four new grid formats" - German, Taiwan, Swedish, and Maidenhead grids. "New Fonts" for improved readability. [Each character is 4 pixels wide instead of 3.] "Re-settable trip odometer" "24 hour or 12 hour with a.m./p.m. time display" Here is some more info from Larry James: What is the size, weight, etc. of the new GARMIN GPS 38? The GPS 38 weighs 9 oz. It uses 4 AA batteries, which last up to 20 hours in battery saver mode. It uses the same "Multi-Track 8" GPS engine as the GPS 40 and GPS 45. It is physically quite similar to the GPS 40. Is the 90 [knot] speed limitation still there? Yes. What does the GPS 40 have that the GPS 38 does not? An MCX connector on the back to connect an active external antenna. What provision is there for computer connection? The GPS 38 is compatible with all the data cables, mounting brackets, DGPS receivers, and commercial software that work with the GPS 40. It is probably compatible with the net freeware also. James Associates will make sure MacGPS is compatible. You will have to check with the authors of free PC software for their policy. Here are some additional new features of the GPS 38: The satellite status page shows an empty signal-strength bar while ephemeris data is being collected for that satellite. Thus you know what satellites are actually being used in the position solution. [This is available on the GPS 40/45 by going into diagnostics mode explained elsewhere in the FAQ.] The GPS 38 is 1 oz lighter than the GPS 45 and the GPS 40. The GPS 38 uses a different type of LCD display. [The GPS 38 display is blue instead of black.] We have checked out both MacGPS and MacGPS Pro with the GPS 38, and both work fine in all modes, no update is required. The GPS 38 does not include a video (unlike the GPS 40). [Larry James, http://www.csn.net/~lwjames] -------------- Some more info: The Garmin 38 is very similar to the Garmin 40/45 with the following differences. What the Garmin 38 has that the Garmin 40 does not: Coordinated System: Maidenhead (used by HAMs with packet) Map Datums: 106 Full Screen Compass with Waypoint Pointer Instant Initialization by Country Trip Odometer Backtrack feature "STN" type [LCD] display AM/PM Time display 9 oz. weight What the Garmin 40 has that the Garmin 38 does not: Antenna connector Map Datums: 103 "FTN" type [LCD] display Internal Alarm beeper Carrying Case User Video 10 oz. weight Paul James ------------------- I got some data sheets from Garmin in the mail the other day, including the 38. Here's a summary ("same" means same as Garmin 45): * Size, weight, display size: same * Case: waterproof tested, ultrasonically welded, dry nitrogen-filled * Magenta LCD display with electroluminescent (EL) backlight * Resettable trip odometer * Coordinates: Lat/lon, UTM/UPS, plus 7 grids, including Maidenhead * Internal lithium memory backup battery * Antenna: internal * Power: 4AA or 5-8 VDC * Does not come with batteries or carrying case * Battery Life: <= 12 h (normal), <= 20 h (saver mode) * Waypoints, routes, datums: same * Operating System: same * Differential-ready (same) * Acquisition times, update rates, accuracy, interfaces: same Donn Mumma ---------------------------------------------------------------------- -GPS II? I have examined the GPS II at a marine store. I would describe it as being like a GPS 45 but with a triangular block shape. It can be used either vertically or on it side because the software can rotate the characters on the display by 90 degrees. The BNC antenna swivels. It also has zoom in and zoom out buttons which are very handy. Zooming in and out is rather awkward to use on the other units in the GPS 45 family. There are also optional mounts: 010-10122-00 GPS II handlebar mount (presumably for bicycles) 010-10111-00 other GPS II mount | ---------------- Here is a very detailed review by Daniel Butler: I recently bought a Garmin GPS II from West Marine (special order from warehouse), and these are my inital impressions. Since I've only had a GPS 38, that's all I have to compare it to. Other than not having an external antenna and different voltage tolerances, the 38 is nearly identical to the 45XL. The GPS II unit has software version 2.02. The 38's is 3.03. Physical: The II is slightly shorter and bigger around than the 38, mostly because of the external antenna, which connects via the standard BNC connector. The battery compartment of the II has a smaller lid with small rubber gaskets that seem to seal better than the 38's awkward lid. The II has more room for the batteries than the 38--batteries that get stuck in the 38 don't in the II. The II has a triangular shaped back, so that when you hold it in front of you in portrait mode, the antenna cannot be made to point straight up like the 45's. There are six screws that hold the back on and sandwich a rubber gasket between the back and the front. The documentation makes no mention of waterproofness or water resistance, and looking closely at the gasket, I suspect that there's not enough screws to maintain the seal's integrity all around the perimeter. A resourceful enough individual, however, could probably get creative enough with silicone to ensure a seal if waterproofness is that important. The rubber cover for the computer/power interface is much easier to open. The II comes with a lanyard and a strip of hook-and-loop fastener for mounting the unit to your dash. But, if you stick the fastener on the II, it will no longer sit flat on a table (it rocks), and the angle it sits on the dash makes it difficult to read. The plastic over the display of the II is inset a little bit more than on the 38, making it less likely to get scratched. The buttons on the II are bigger and spaced better, and the rocker switch has little bumps on it, making it easier to feel in the dark. There is also an inset screw hole on the back side for mounting it to something--probably one of those overpriced accessories Garmin wants to sell you. Display Quality: The II's display is identical to the 38's in the light, the same green color with blue text and graphics. The nighttime display is very different. The 38 is lit by a bright blue or turquoise backlighting (bright, but hard to read), whereas the II has three levels of yellowish-green backlighting (dimmest, dimmer, and dim). In total darkness the II is actually easier to read--it doesn't kill your night vision either, and I imagine the II's lighting has much less battery drain. (The 38 is like a flashlight at night, actually). The II's display is hard to see near dusk on the dashboard in any stage of lighting. Little-known Features: Holding ENTER when turning the unit on still initiates the test page, as does ZOOM OUT and pressing the rocker switch UP, to the RIGHT, or diagonally UP/RIGHT while in portrait mode. While in test mode you can test if buttons are working, or press ENTER to see some interesting pattern tests. Turn the unit off to get out of the test. Holding MARK down while turning the unit on will do a hard reset, after which the GPS II knows nothing and must search the sky for satellites to refind itself and relearn the date. Only the very patient want to do this, because it takes quite a while to find and then autolocate. All waypoints, routes, and track info are deleted. Holding PAGE while turning on does, I guess, a soft reset, which the time is remembered, but the position is not--and you must do either an autolocate or quick locate. The GPS 38 didn't have this feature, but I can't imagine why I would ever use it. By pressing the four cardinal directions on the rocker switch immediately after turning on, you can enter a debug mode, just as with the 38, with the same D-menu (diagnostics) and extra numbers on a couple of screens. I get the greatest success with the UP-DOWN-LEFT-RIGHT sequence. You can't get the spinning logo on the moving map page anymore by holding the OFF key for a bit. In fact the cool spinning logo is gone and replaced with a new, rising earth with disappearing horizontal lines. Kind of primitive animation, actually. Some things are better left unchanged. New Features: o Switch between portrait or landscape mode by holding down PAGE. o ZOOM IN or OUT keys that work on the moving map page. You can pan any direction, including diagonally, with the rocker switch--no need to change from ZOOM to PAN modes like on the 38. Very nice. o TRACK OPTIONS and MAP OPTIONS are available from the moving map page by pressing ENTER, instead of having to go to the menu page. o On the satellite status page, the contrast can be adjusted with the rocker switch. o Waypoints names have a bigger font on the waypoints list. I don't like it as much, though. o On the compass page, you have two user-selectable fields in which you can display either total time in travel, average speed, maximum speed, altitude, trip odometer, or elapsed time. When you reset one, it resets the others. Very cool, especially since total time in travel and average speed only counts the time you're actually moving. Great for knowing how fast you walk while hiking or while paddling on a river. o On the goto waypoint page, you have one slot available for viewing one of ETE, ETA, CTS, XTK, VMG, or TRN, which all have meanings, but I don't have the documentation here right now. o It only takes two seconds to turn off instead of three. It's the little things... Performance: From what I can tell about setting it side by side with the 38 and leaving it on for quite a while, the II doesn't use as much battery power as the 38. Not much less, but there seems to be a noticeable difference. The difference is probably be more significant if you use the light regularly. The reception in my 38 is very good, even under canopy one a fix is obtained, but I have never gotten it to pick up inside the house. I did manage to get a 3D fix with the II. Quite amazing. Sitting in the windowsill facing west, I could track five satellites. Outside on a clear day away from obstructions, both pick up quite well, but the signal bars on the II are probably 10-20% longer than those on the 38, on average, and the EPE is usually less. In more marginal conditions, like on my dash driving around town, the II could had a fix with 6-7 satellites, while the 38 had never even gotten a 2D lock--and they were turned on at the same time. When turned off and turned on again in clear view of the sky, it is a little quicker acquiring the birds (by a couple of seconds) than the 38. This is probably a result of the better antenna. Compatibility The GPS II works with Street Atlas 4.0, Map 'n Go 2.0, Waypoints+, Garlink, and WinGPS 3.92 just fine, as far as I can tell. I hope this information helps anybody that's thinking about buying one of these units. Daniel Butler --------- Here is yet another detailed GPS II review by Paul Menconi: Experience with the Garmin GPS II GPS hand-held receiver Garmin has recently expanded its line of hand-held GPS receivers. Of particular interest to me is the GPS II. Last year I borrowed a 45 (the "45 classic") for three months, including a week of bare-boat chartering in the Virgin Islands, and was quite impressed with its capabilities and ease of use. The II seemed to fit my needs better, but before buying one I was concerned that I wasn't giving up any of the capabilities of the 45. The 45 has been replaced by the 45XL, which looks identical but has some added functions. After some consideration I finally bought the GPS II. I herewith offer a modest comparison of the new GPS II and old 45. Hopefully this will be useful to others in making the decision of which hand-held GPS best suits them. It appears from the specifications that the new Garmin 45XL and GPS II are identical internally. The obvious external differences are driven by different intended uses. It's clear the 45XL is still Garmin's premiere small handheld, intended for marine use. The GPS II has an identical display and controls layout, but at around $US250 is $40 or so cheaper than the 45XL. While the 45XL retains the nitrogen filled, welded plastic case, the II is held together by screws, with a thick rubber gasket between the case halves. Construction aside, the main difference between the 45 and the II is the shape of the case. While the 45 is rectangular in cross section, the II is more of a rounded triangle. This shape, and a slight relocation of the external antenna, allows the unit to be set lengthwise on a table (or dashboard), with the screen tilted at a convenient reading angle. Of course, the 45 could be propped up on its side, but the display would be sideways. Holding in the Page key on the GPS II, though, rotates the display image 90 degrees, so that everything is right side up. The GPS II has the same buttons as the 45, arranged in the same fashion, and performing the same functions. At the far end of the case, though, top or right, depending on orientation, are two extra buttons. These are the zoom buttons, In and Out. The zoom function has been moved from the track display graphic screen to these dedicated buttons. This method is more convenient and certainly less confusing than the way it was done on the 45. It is one, and I think the only, added feature the 45XL does not share. The five screens of the 45 are retained, and are accessed in the same order. However, there are some changes. The differences are listed here: Satellite Status Page: The battery level indicator does not go away when connected to an external source. The satellite signal strength bars are hollow when the receiver has found the satellite and is collecting data. The bars turn solid only when the indicated satellite is being used. Screen contrast may also be adjusted from here by pressing the "rocker keypad." If a position fix is not found within some period of time, or if the unit has traveled more than 500 since its last fix, it enters the "EZinit" mode. This mode is used when the unit is really confused about where it is. The user is offered three choices: select from a country list (which offers an approximation of the current lat and long); do an autolocate, in which the unit spends some 15 minutes reading all the satellite info in order to fix its position; or an "ignore EZinit" mode that continues acquiring. EZinit is an interesting addition, but not really necessary. The original 45 had the autolocate feature, which allows the unit to find its location after being seriously displaced. The first fix can be greatly speeded up by manually entering the approximate lat and long, which in effect is what the "EZinit" feature does, although it requires scrolling through a long (very long -- at last we can figure out where Bosnia-Herzegovina is) list of countries and states. Position Page: Same as in the "45 classic," with the addition of two user-configurable fields. One of these takes the place of the old "Alt" field, and the other is squeezed in above it. The first of these fields can be set to any of the following parameters: TRIP: trip odometer; distance traveled since reset (a much-requested feature, with resolution to 0.1 miles for the first 99.9 miles and 1 mile to 999 miles. I don't know what happens after that.) AVSPD: Average speed since reset (Resets with Trip and/or Ttime) MXSPD: maximum speed traveled since reset TTIME: trip time; total cumulative time during which a ground speed was maintained (An interesting feature, although I can't imagine it being widely demanded. Resets with Trip and/or Avspd) ELPSD: elapsed time; total cumulative time since reset All of these parameters are easily resettable. The other field may be set to: ALT: altitude above sea level TTIME ELPSD TRIP Of particular interest is the TRIP function. This actually does measure the total distance traveled, not just the straight-line distance between points. Trip time, TTIME, is a timer that runs only when the ground speed is about one or two mph. Presumably it is used, with the TRIP distance, to calculate the average speed. Map Page: This is the graphic track display. Numbers in the corners display bearing and distance to the next waypoint (upper left and right corners, respectively), and the current track and speed (lower left and right corners). The main change in this screen is that the map and track setups are done from this page, not from the set-up page. I think this was done partially because there is not enough room on the set-up page for the whole list of items to be set up when in the horizontal display mode. By moving the track and map set-ups to the map page, there is enough room on the set up page for what's left. The result, though, makes sense. It's much easier to change the settings without having to change screens. Compass Page: The "45 classic" had the "highway" page, a graphic giving steering guidance to a destination. This display is retained in the GPS II and the 45XL, and is augmented by another display that is simpler, easier to understand, and that makes more sense for use on roads and highways. The display consists of a circular "compass" with the cardinal points, N, E, S, and W, displayed on the outside. The compass rotates so that the direction of travel is always at the top. Inside is a thick arrow indicating the direction to the next destination, again with the current direction of travel at the top. While the highway display is excellent for steering a boat, driving on a road or hiking on a trail offers far less freedom in direction of travel. This new display is well suited for use where the terra is more firma. Both the "compass" and "highway" displays show the bearing and distance to the destination waypoint in the upper corners and the current direction and speed in the lower. The characters for these readouts are larger and more easily readable than in the previous model. At the top center is listed the name of the destination waypoint. At the bottom center is another user-definable field. Options available are: ETE (default): estimated time enroute ETA: estimated time of arrival CTS: course to steer XTK: cross track error VMG: velocity made good TRN: turn; the amount of correction in degrees needed to travel directly to the destination Changing from the "highway" display to the "compass" display is simply done by pressing the Enter key twice. Setup Page: Essentially the same as the 45, except that the track and map setup entries have been moved to the map page. Waypoint Page: No changes here, except a larger font is used for the waypoint names. They are noticeably easier to read. So let's see, what else? The II comes with virtually no accessories. It does not include a case. It does include a strip of Velcro that can be stuck to the bottom of the unit. (I put the "hooks" part on my GPS II, which then stuck like crazy to my fuzzy dash cover.) Like the original 45, it comes with a thin wrist strap that makes me think of a g-string (both in its appearance and in the protection it offers). The strap ties to a wire loop on the battery door. The manual is thorough, although it won't stand up to heavy use, in contrast to the 45's spiral-bound booklet. The antenna of the GPS II comes off just like the 45's, leaving behind a standard BNC connector. The same power and data cable fit both the II and the 45. I was able to download data from the 45 using a Garmin data cable connected to my PC's serial port. I haven't yet had a chance to try that with the II, but will eventually, and don't anticipate any problems. The manual for the II states that the unit will drive three NMEA devices using NMEA 183 ver 2.0. Literature for the 45XL claims NMEA 180, 182, and 183. This may be a significant difference if you plan on using the unit to drive an autopilot or other NMEA devices. The display on the 45XL is noticeably clearer and darker than that on the II. Both displays are clear and readable, but the 45 display might work better under marginal conditions. And, Garmin is finally including a notice in their literature about the 90 MPH speed limitation on their non-aviation GPS receivers. All in all, I like the GPS II and its new software features. Like I said, I'd get the 45XL for primarily marine use, but it is obvious that the II is intended for use in vehicles. The salesman where I got mine told me that Garmin will be selling a bicycle bracket that clips into recesses molded in the case, allowing the unit to be mounted on the handlebars (or a boat's stern railing, perhaps). The owner's manual admonishes the new user to fasten the unit securely so it won't fly about the vehicle, and to pay attention to the road while driving. This last is no joke: if you think cellular phone use while driving is dangerous, wait until you're behind someone on the freeway driving with his knees to keep both hands free for punching buttons on his GPS. I've found that my GPS fits well on the little shelf in front of the speedometer in my car. It even gets reasonable satellite reception there. For the last few weeks I've been driving around trying out the various displays (but always with one hand on the wheel!). I've concluded that the usefulness of GPS on the highway is limited to places you've already been recently. Once you've got some waypoints set in and a route estabished it's great for predicting time of arrival. It's rather pointless, however, to expect it to lead you directly to your destination, since you're confined to the road. I think the next step is to interface the GPS with map software on a laptop.... Paul Menconi ---------------------------------------------------------------------- -GPS 12XL? | This is the very long awaited compact true 12 channel unit and it does NOT have the 90 knot speed limit! It also apparently has flash memory so that the firmware could be uploaded from the serial port. I was able to buy a returned GPS 12XL (on an impulse) from West Marine and have had a great time playing around with it. My first impressions are that it is more sensitive under trees and the user interface is very much like the 45XL/38/II. I haven't had an opportunity to do a side by side comparison with a 45 or 38 yet. The position averaging feature is rather convenient. I really miss the BNC swivel antenna of the GPS 45XL for use on the dash of my car. The external antenna connector (MCX) is obscure but is used by a couple of other Garmin models. I hope they come out with a BNC swivel antenna version sometime. If you are not put off by the lack of a BNC swivel antenna, this is the small handheld model to get for hiking in thick trees. Due to some reservations I had heard about the battery life, I put in a brand new set of alkaline batteries and they lasted 12 hours, 25 minutes. (Lane Holdcroft) | ----------------- Larry James posted the following about the GPS 12XL: Most of you have been waiting and wondering and hoping. The wait is over. Garmin announces the new GPS 12XL Professional Navigator for challenging environments: PhaseTrak12 parallel channel receiver for fast position fixes in tough conditions, including tree canopy and urban obstructions. GPS 40 style and size case with built-in antenna now meets stringent military 810(e) environmental specifications. 500 waypoints, 20 reversible routes, over 1000 track log points. Proximity waypoint alarms with beeper. TracBack and the other GPS 45XL features, plus position averaging and user-programmable datum. The great battery life Garmin handhelds are known for (up to 12 hours using 4 AA Alkaline batteries). Larry James, James Associates, http://www.csn.net/~lwjames ------------------- Here are some more detailed specs that were received by Lee from a FAX from Garmin: NAVIGATION FEATURES Waypoints: 500, Nearest 9 (automatic) 9 proximity Routes: 20 reversible with up to 30 points each, plus MOB and "TracBack" modes TracBack: Automatic track log navigation Map Datums: 107 including 1 User definable Datum Coordinates: Lat/lon, UTM/UPS, plus 7 grids, including Maindenhead and user UTM. PERFORMANCE Receiver: PhaseTrac12 receiver(12 parallel channels) continuously tracks up to 12 satellites to compute and update position Acquisition Times: Warm: approx 15 sec, Cold: Approx 45 sec, Autolocate: Approx 5 min Update Rate: 1/sec continuous Accuracy: Position: 15 meters (49 feet) RMS (subject degradation to 100 meter due to SA) Velocity: Performs to 999 kts, .1 knot RMS steady state Dynamics: 6 Gs Interfaces NMEA 180, 182, 183 and RTCM 104 DGPS corrections Antenna: Internal Patch (External antenna optional) PHYSICAL Size: 2.1"W x 5.8"H x 1.2"D (5.3x14.7x3.1 cm) Weight: 9.5 oz(269g)w/batteries Display: 2.2"H x 1.5"W (5.6x3.8 cm) high contrast LCD with electro luminescent backlighting, Case Ultrasonically welded Temp Range 5 to 158 Deg F (-15 to 70 C) Memory Backup: Internal rechargeable lithium battery POWER Source: 4AA batteries or 10-40vDC Battery Life: Up to 12 hrs. ACCESSORIES Standard: GPS 12XL Receiver, 4 AA Batteries, User's Manual, Quick Reference Guide, Carrying Case, Wrist Strap. Optional: Mounting Kit, Data Transfer Cable, Cigarette Lighter Adapter, PC Kit External Antenna There is also a note stating "Specifications are preliminary and subject to change without notice." Please excuse any typos and spelling errors Lee -------------- Here is a detailed 12XL review by Lewis Schnaper: So when I heard about the 12XL it sounded like the next best thing. FWTH, here are my notes on a couple of day's use of the new unit. January 17, 1997 I got a 12XL yesterday at Northern Lights Avionics in Anchorage for $265. My first and strongest impression is that the receiver is incredibly sensitive and quick. I've got a 38, and have only been able to get a fix in the house by putting it by a window and waiting, and often no fix results. The 12XL gets four or eight satellites in the middle of the house, and I've gotten a fix from power-on in as little as 14 seconds, while the 38, in a similar position is getting one satellite, at most. Strangely, the signal strength indicators some times go up when the unit is held vertically. Physical: the case is almost identical with the 38, but for a slightly different angle to the antenna. One 38 feature that is missing is a molded in attachment at the top for the lanyard. Instead, you're left hooking the lanyard to the bail that opens the battery compartment. Display: this is a slightly different screen than the 38. The text appears to be the same pixel size, but the 12XL is dark gray on light gray, rather than the dark blue on olive of the 38. In light I'd say the 38 is a little easier to read, while in the dark with the backlight, the 12XL is more visible. Screens: On the satellite status page the only difference is that the bars are smaller because it shows 12 satellites versus 8 on the 38. On the position page, the aircraft type compass reads compass points (N-NW-NNW) rather than the 38's mix of N-345-330-NW. I don't see a way to alter this in the setup. In the 38 on this page you could change the trip length, altitude, and enter a position. I figured that this was for initialization, but never confirmed that. On the 12XL, you can only change the trip length. The map and steering pages look identical. The arrangement of the setup menu is different, but many of the elements are the same. Some differences are the ability to set 9 proximity waypoints and a distance from each, and the unit will then warn you when you are within the specified radius. There is also a user-definable grid and datum. The unit does have an audible beeper, which can be set to messages only or messages and keystrokes. My preference would be to have the message screen come up automatically, but on the 12XL you still have to hit page. One interesting new function is that when you mark an waypoint you can hit an average key then watch as the FOM "Figure of Merit" decreases. This seems to happen pretty quickly--like 10 seconds, and seems to start at around 100'+ and go down to around 60'. I'm not sure what's happening here, but assume that this is the confidence radius for the position. You can still get into the test mode by holding Enter when you power up. [To get into the diagnostic mode, you must press all 4 arrow keys and hold them a little longer than you would on the 45 or 38.] Also, the globe rotation animation is gone, as is the trick for adjusting the world's spin speed and direction. The content manual is similar to the 38, not very technical and a number of features are not well explained. The wire comb binding is a little too small for the number of pages, and I'd guess that pages will start to fall out with much use. The unit comes with a little nylon case, which looks like it was cut to fit a bigger unit or, more likely, one with an external antenna. I'm going to take both units out on snowshoes this afternoon and see how they work outside, but based on first impressions the 12XL is going to offer a significant performance improvement for hiking use. If the battery life turns out to be shorter than a full day, the 38 may still be preferable for boating, if no external power is used. January 19, 1997 I did a five mile snowshoe with the unit yesterday in an area with about a third of the sky covered by a high ridge. I left the unit on for the whole walk, and as far as I could tell it tracked continuously, despite the limited sky and the fact that it was in the breast pocket of my jacket and sometimes the antenna was faced in towards my chest. I was impressed with the performance. Battery life is still a concern. This was the original set of batteries, but they seemed to go long before ten hours. I did find that there was an hour or more of operation left after the "low battery power" warning went off. Another factor may have been that the temperature was down in the 20s. Lewis Schnaper | ------------ Here is another GPS 12XL review by Philip Blair: Well I've had a chance to play a bit with my 12XL and so far I'm still well impressed but to be honest I would probably be just as happy had I bought a 38. The drain on the battery also seems to depend greatly on how many satellites are being tracked. On the other hand I have been well impressed by the ability of the unit to hold on to satellites, now there is no way you see a bird through a mountain but it has managed to have 7 up in my bedroom. In view of the metal blinds and the like this amazed me. I did a few tests by turning the unit off and walking a few hundred yards, then turning the unit back on. It had a fix in about 15 seconds, as claimed by Garmin, and I don't think that I can complain about that. The software works very well for me, now this is my first GPS and I will still be navigating with a map and compass for most of the time, the GPS is just a safety aid. However I have entered a few waypoints, made up a route and followed the moving map and it works. In fact it works so well that I would be concerned that some users would be tempted to leave the map at home and just follow the GPS. The "TracBack" function allows the user to sally forth while the 12XL takes care of deciding where the waypoints should go. You can then use this "robotic" list of waypoints to guide you back. Now for me this is a function which will rarely be used but I would imagine that it would be very attractive for some users. I've tried it and it works, it seems to use 1024 waypoints as it goes along and it then rationalises these down to 30 waypoints to make up an active route. Probably best to use this for fairly simple routes I suppose, just in case it rationalises out that detour around the cliff top :-) For some people the speed limit thing was a big deal and the manual says that there isn't one, quote: "performs to 999kts, 6g dynamics.". Now I haven't tested this but it is unlikely that Garmin are making it up. The only big down point is that there is a fortune to be made by someone who can produce a shock proof, waterproof case which will go on a belt or rucksack strap. If the unit could be operated while in this case then all the better. There seem to be thousands of companies out there willing to sell you expensive portable gear but very few of them are willing to help you not break it. Bottom line: If I had to do it again I'd still buy a 12XL but most 38 owners shouldn't lose any sleep. Philip Blair ---------------------------------------------------------------------- -GPS 89 (aero)? The GPS 89 is a GPS 90 with a much less complete jeppeson database (only has airport and VOR locations) and fewer accessories. It does not include the yoke mount but it does include an antenna extension. | Here is an extensive review from Derek Ruddock: Here are my initial impressions of the Garmin 89 GPS system. I bought the Garmin for use when I fly sailplanes. The unit has an international Jeppesen database of airports and VOR's, but without the useless (for me) data such as fuel availability and runway layouts found in the more expensive GPS90. For this review, I will follow the layout of Gavin Scotts review of the Garmin GPS40 posted on 27 Apr 1994. I bought my unit on 22 July 1996, from Eastern Electronics and paid $449 USD. Shipping and insurance via FedEx to Sydney cost an additional $50 USD (Ouch!). PHYSICAL DESCRIPTION: The spec sheet lists the dimensions as 15.6 * 5.1 *1.23 cm (6.15 * 2 * 1.23 inches). Weight is 269 grams (9.5 ounces) with 4 AA batteries included) At the top on the right side is a recessed BNC connector where the tiny (7cm * 2cm * 2cm approx) antenna is attached. The dimensions of the main unit given above do not include antenna, which makes the top of the unit about 7cm (3 inches wide) overall. At the top of the unit is a four way rocker switch surrounded by six other buttons. This layout allows the unit to be easily held in either hand with the thumb operating the buttons. The joystick like flat rubber rocker switch is used for all data entry. Alpha-numeric data is entered by cycling through the possible letters/numbers. To the left of the rocker 'cursor' button are (top to bottom) GOTO NRST: sets direct course to a selected waypoint, or by pressing twice displays the nine closest locations. Power/Backlight QUIT returnd to previous page or clears & restores previous value To the right are PAGE: cycles through the available pages WPT: displays Jeppesen Airport & VOR's plus up to 250 User waypoints ENTER: confirms data entry. The top 1/4 of the front is blank except for an embossed logo). Beneath the switches is the large LCD display which takes up the bottom half of the front of the unit. The display has a 'portrait' orientation, and is twice as high as it is wide. The unit is completely black. Batteries (4 AA alkaline) are inserted into the bottom, by rotating the thumb loop 1 quarter turn anti-clockwise. A 4 pin Garmin connector is at the base of the back of the unit. The pins are described in the manual as Ground, Power in ([10]-40V DC), and DATA IN | and DATA OUT. A rubber plug protects the connector when it is not in use. The whole unit is filled with dry nitrogen and the ultrasonically welded, and is covered by the one year warranty. ACCESSORIES INCLUDED: BNC cable with bracket and suction cap (for remote mounting of the aerial) 4 AA [alkaline] batteries (installed). Carrying case (black vinyl leathercloth with belt loop and Garmin logo in white. Reference manual (63 pages, dated April 1996). Quick reference card Warranty registration card. Wrist strap. Everything comes in a white cardboard box . SPECIFICATIONS: Temp range 5-158 degrees F (-15 to 70C). Acquisition times: 20 seconds (warm), 2 minutes (cold), 7.5 minutes (sky search). Update rate 1/second (continuous) Position accuracy 5-10M (with DGPS), 15M RMS (without SA), [100 Meter accuracy with 95% confidence (with SA on, as is the case now)] Dynamics: 3g's. Power usage .75 watts. Battery life 12 Hours normal, 20 hours battery saver mode. NMEA INTERFACE INFORMATION: NMEA 0183 Version 2.0. Approved sentences GPGGA, GPGLL, GPGSV, GPRMB, GPRMC, GPRTE, GPWPL, GPBOD Proprietary sentences PGRME (estimated error), PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control). Five I/O options are available: Garmin/Garmin using their proprietary interface, None/None, None/NMEA, RTCM/None and RTCM/NMEA. DGPS corrections are accepted from any RTCM-104 v2.0 format compatible beacon receiver, Garmin's GBR 21 being the recommended receiver. OPERATIONAL DESCRIPTION, FEATURES, PRELIMINARY EXPERIENCES: To turn it on, you press the power/backlight button and hold for 2 seconds. The welcome page displays "Welcome to the Garmin GPS 89" and it gives the firmware revision as "2.07" as the unit performs a self test. After the self test, the Jeppesen database information is displayed (in my case "Worldwide Cycle 9604 effective 28 Mar 1996 to 25 Apr 1996") (yes it has expired!.) this fades after a seconfd or two and the satellite status page is displayed. This display shows the position in the sky for each satellite, a bar graph of the signal strength of up to 8 stats at a time, a large battery power gauge bar, a backlight indicator , and a status message ("Acquiring" etc). Pressing the PAGE key cycles through the main displays which are as follows: POSITION PAGE: Shows (from top to bottom): Compass display (like looking at a compass from eye level). Track and speed Trip Distance and Altitude Position in LAT/LON down to .001 minutes resolution Time (either local time or UPS depending on preferences) to 1 second. MAP PAGE This is a moving map display. At the top of the map are three options for zoom range, pan and configuration. The autozoom feature will automatically keep your current position (signified by an aircraft icon in the lower centre of the display) and your next waypoint on the screen. This can be manually overridden. As you get closer to the waypoint, the map will automatically change scale to keep you both on the display. Depending on the (user selected) setup, the airports/VOR's/user waypoints are displayed using their ICAO prefix. The display can be tailored to suppress the display of this data if desired. Selecting a waypoint and pressing enter displays details of the waypoint. You can zoom manually 0.5 TO 600km (0.2 mile up to 320 miles). In addition it is possible to You can have TRACK UP or NORTH UP as you like. NAVIGATION PAGE Shows (from top to bottom): Bearing and Distance to next waypoint Track and Ground speed CDI scale (Course Deviation Indicator) with Relative Bearing Pointer (arrow showing the direction to the next waypoint) ETE/ETA and Crosstrack Error Time and VNAV altitude MENU SCREEN: These options lead to other configuration menus. Shows (from top to bottom): E6-B Menu (power jockey functions) Alarms/CDI User Wpt List Routes Messages Audio/Display Units/Datum Date/Time Track Log Interface OTHER MISCELLANEOUS STUFF: EZinit: to speed up initialisation, enter your approximate location (Very easy if you are at an airport, just select one from the built in database) You can input 250 Alphanumeric waypoints with (6 character name, 16 character comment) 20 reversible routes with up to 32 waypoints each. Pressing GOTO twice stores your current positions as a waypoint. Other functions: Sunrise/sunset calculation, vertical navigation , Winds aloft calculation, trip and fuel planning , proximity alarms, countdown timer, All the usual config options are there (Statute, Nautical, or Metric units, True, Auto magnetic, or Manual magnetic headings). You cannot mix units (eg I would like to measure my height and speed using nautical units, but distances using km. This is not possible.) There are dozens of map datums(data?) to choose from. Positions can be displayed in DDDMM.MMM or DDMMSS.S format or UTM coordinates, or British, Irish, or Swiss GRID formats. CDI scale can be +-.25, 1.25 or 5 Miles or kilometers. You can choose to display CMG/VMG rather than track/speed. There is a simulator mode [which simulates strong satellite reception so you can practice operation of the unit indoors]. The differences between normal and battery saver mode are not described (other than to say that battery save mode saves 50% of the battery power and is "suitable for most applications". Derek Ruddock ---------------------------------------------------------------------- -GPS 90 (aero)? The GPS 90 comes with either a US or International (UK and Europe) database. If you buy it in the US, make sure you get the database you want. John Mccurdy The Jeppesen database is updated regularly and the update cost is about $125 for one time, $312/yr for quarterly updates, and $845/yr for 28-day cycle updates. If you let it expire, then you will receive a warning message on every powerup that the database is out of date but you may continue operation. The Garmin GPS 90 looks like the GPS 45 except that it has different firmware, a dark grey case (top and bottom), and a couple of buttons are relabeled. Internally it has more battery backed up memory and may have better shielding. Of course it does not have the 90 knot speed limit and it has some other software features for aviation use such as a database of public airports and navigation aids. I found the following press release which was posted a while ago. Some additional info and specifications from a recent posting follows the press release. Start of press release: ----------------- Subject: GARMIN introduces GPS 90 Organization: GARMIN International Date: Tue, 4 Apr 1995 15:25:38 GMT Essentially, if you know the GARMIN product line, this is a 45 and a 95XL all rolled into one package. FOR IMMEDIATE RELEASE: April 9, 1995 GARMIN Introduces Powerful GPS Receiver in Small Package The GPS 90, the world's smallest handheld GPS, is packed with all the features of its larger counterparts LENEXA, Kan. GARMIN International, aviation's leading GPS manufacturer, announces the introduction of the GPS 90, the world's smallest GPS handheld receiver. At only 10 ounces, and about the size of a remote control, the GPS 90 is full-featured, with moving map graphics, a large LCD display and an extensive Jeppesen database that includes all airports, runway diagrams and available navaids and SUAs, all at the pilot's fingertips. Significantly, battery life for the GPS 90 is approximately 15 hours on only four AA batteries, greatly exceeding that of any other GPS receiver to date. The ergonomic design of the GPS 90 truly is a breed apart from other models in the marketplace. Specifically, the GPS 90 is designed to fit comfortably in the pilot's palm for single-handed operation. Or, the unit mounts nicely in a universal yoke mount, which is an included accessory with purchase. The GPS 90's unique thumbkey rockerpad offers two scrolling speeds and quick, intuitive data entry. The GPS 90 will bring many pilots into the GPS fold for the first time, said Tim Casey, GARMIN's aviation marketing manager. Its size, simplistic software operation and amazing battery life make it the one piece of equipment every pilot's bag should make room for. The GPS 90 has a unique, rockerpad cursor control and only six function keys, enabling pilots to quickly access one of five main pages that are displayed on the EL backlit LCD screen. Those five pages are: satellite status, position, moving map, navigation and menu. The satellite status page shows which satellites the receiver is tracking, the strength of their signals, and also displays the battery power via a graphic fuel gauge. The position page indicates your track, speed, latitude, longitude, altitude and time-of-day. The moving map graphically plots your course as you mark waypoints and travel waypoint to waypoint. The map is capable of 12 range scales from 1/5th to 320 miles and will also zoom and pan the area you're navigating. Pilots may also view airports, VORs, NDBs, SUAs and other user-chosen information provided by the internal Jeppesen database. The navigation page indicates your bearing, distance, track and speed to an active waypoint. A course deviation indicator tells you when you're off course. The menu page offers pilots various setup and user-preference options, an E6-B menu, sunrise/sunset calculations and route and waypoint management features. GPS 90 users may also choose to operate the unit at home in the simulator mode to plan trips, customize user options and enter or modify waypoint and route information. The unit will store 250 user-defined waypoints and up to 20 reversible routes, with 30 waypoints each. Additionally, the case for the GPS 90 is ultra-sonically welded and dry-nitrogen filled. The GPS 90, along with the entire GARMIN product line, relies upon GARMIN's proprietary MultiTrac8 receiver technology, which tracks and uses signals from up to eight satellites simultaneously. The GPS 90 comes with a carrying case, user's manual and quick reference card, wrist strap, universal yoke mount bracket, suction cup antenna mount, power-data cable and a cigarette lighter adapter. Optional accessories available for purchase include a serial data cable and PC kit. The GPS 90 is currently available and lists at $799. GARMIN International designs, manufactures and markets GPS equipment for a variety of markets, including aviation, marine, military, survey, OEM and general recreation. For more information on the GPS 90 or any of GARMIN's other GPS receivers, contact GARMIN International [see new address at end of FAQ]. [End of press release] ---------------------- Here is some info about the GPS 90 supplied by Roger Vermeir: Controls are the same, except for some key labels: 'GOTO' on the 45 is called 'GOTO NRST' on the 90 'MARK' on the 45 is called 'WPT' on the 90. Here are some specs of the 90: up to 250 user waypoints; up to 20 reversible routes (with up to 30 wpts each) acquisition: warm approx. 15 sec (I've had several in less than 8 sec, in good conditions) cold: approx. 2 min autolocate : approx. 7.5 min (but it may need up to 15 min, and if you are in a real 'Poor GPS coverage' area, it will start beeping and then auto shut-off) update rate 1/sec (cont) accuracy: position: 15 m (49 ft) RMS (100 m 2DRMS if DoD's SA is ON) velocity: 0.1 kts RMS steady state [several kts realistically because SA is ON] Dynamics: 999 kts velocity, 3 G's Interfaces: NMEA 180, 182, 183, unit-to-unit, PC, RTCM 104 v.2.0 (corrections) MAP datums : 105 size: 6.15 x 2 x 1.23 inches (15.6 x 5.1 x 3.1 cm) weight: 9 ounces (255 g) inclusive batteries display: 2.2 x 1.5 inches (5.6 x 3.8 cm) high contrast backlit LCD case: ultrasonically welded, dry nitrogen filled power: 4 AA batteries or 8...40 V DC 0.75 W max consumption Temp. range : 5 F to 158 F (-15 C to + 70 C ) Battery life: up to 15 hours (normal mode) or 20 hours (battery saver mode) Built-in rechargeable lithium battery saves almanac and waypoint data while you are changing batteries, BUT WILL ONLY SAVE DATA FOR A FEW MONTHS (according to the Garmin manual). Roger Vermeir ---------------------------------------------------------------------- -GPS 120? The GPS 120 looks like it has GPS 45/40 software but it has a mobile mount (sort of like the GPS 65), a much larger display, no battery compartment, and it includes an external antenna. It looks like it was intended to be permanently mounted in the cockpit of a boat. The only differences I can see is that the GPS 120 has a Man Over Board button and an anchor alarm option in the menu. Power input: 10-40 VDC, 2 watts The specifications are virtually identical to those of the GPS 45. The GPS 120 sells for less than $400 US discounted. ---------------------------------------------------------------------- -GPS 130? The GPS 130 was Garmin's first 12 channel GPS unit with a display! The GPS 130 looks like the GPS 120. It has a mobile mount unit with no battery compartment. It has a much higher resolution display than the GPS 120 and it also has grayscale capability. It includes a map of the world but also uses optional very detailed map cartridges. Someone measured the current and said it was about 150mA at 12 VDC (without the antenna). See the GPSMAP 175 for more information because the units are similar. | ---------------------------------------------------------------------- -GPS 135? Here is an announcement about another new unit: Garmin announces the availability of the GPSMAP 135 Sounder. It combines the PhaseTrak12 parallel channelGPS engine and an advanced sonar sounder with fish-finding capabilities. Larry James (http://www.csn.net/~lwjames) ---------------------------------------------------------------------- -GPSMAP 175? It started shipping late August 1996. It has a much higher resolution display than the GPS 45/40/38 family. Here is Larry's announcement for the newsgroup: GARMIN announces the GPSMAP 175, a big screen handheld with a 4-level gray scale LCD display and the PhaseTrac12 parallel-channel GPS engine. Takes G-chart cartridges for background maps. Larry James (http://www.csn.net/~lwjames) 250 waypoints 20 reversible routes, 30 points each > 100 map datums Well I couldn't wait, so I called Garmin Sales and Marketing to ask about this unit... Here's the info I got from Lee, GPSMAP 175 Introduced 7/10/96 Dimensions ........................ 7.6"x2.9"x2.1"[19.3x7.4x5.3cm] Weight ............................ 1.4 lbs [635g] Max power consumption ............. 1.5 Watts Display size ...................... 2.25"x3.38" [4.1" or 10.4cm diameter] Pixel count ....................... 160x240 Power needs ....................... 6 AA cells which can last up to 10 hours. Antenna ........................... Internal Patch Will accept 6-40 volts DC external power. Can accept optional active antenna. The person(Lee) I spoke with definitely referred to this receiver as a 12 channel receiver. This is all I asked about, as they were my main questions. I assume the software is much like the G38 with additional Charting capabilities. Glenn Wiltse ----------------- Here is a GPSMAP 175 review by Rick Prelinger: What follows is a nontechnical evaluation of the new Garmin GPS175. I hope it will help readers of this group with their purchase decisions. I ordered my Garmin GPSMAP 175 from West Marine, receiving it on November 29th. Availability is spotty but at that time some units had arrived in their West Coast warehouse. My unit is software v. 2.28, internal database v. 2.01. The unit resembles an expanded GPS 38, except that the orientation of the control buttons and screen is slightly different. Its dimensions are 7.5 inches high, just a shade under 3 inches wide, and 2 inches deep. Weighing something over a pound (I don't have a scale handy), it is best carried in a deep coat pocket or in some kind of cushioned case. It's heavy but you get used to the weight rapidly, and its improved acquisition time makes it easier to hold, because you won't be holding it for very long. The LCD display is perhaps the unit's most striking feature; it's a three-level grayscale display with fairly high resolution (I don't have the manual handy, either), 2.375 inches wide by 3.5 inches high. It's protected by a clear plastic shield that appears to be easily scratchable. There are ten control buttons, pretty much standard high-end Garmin buttons. The two added buttons not present on my previous unit (a GPS 45) are the "Zoom" up/down button, used for controlling map scale, and the "Menu" button, which leads to context-sensitive help menus. Pressing "Menu" once leads to the local menu, relevant to the page you are currently in; pressing it twice leads to the Main Menu, which looks a lot like the main menu on the 45 at first glance, but many of the submenus are more sophisticated. After the unit is turned on a warning screen full of text comes up. You need to press the "Enter" key to get rid of this. It's basically a disclaimer for the electronic chart, that it isn't intended to replace the use of official government paper charts. Another Garmin product liability concern, which gets old very quickly. It'd be nice to bypass this screen; maybe another user knows how to do this. The display is excellent. The only problem from my point of view is just what another writer in this group mentioned -- it isn't always visible from every angle. When I rest it between the windshield and dashboard cushion of my Honda, I find that I sometimes have to shift my head or reorient the unit in order to see the display clearly. Nevertheless, the typography and graphic design is readable. For many this may be one of the greatest consideration in favor of this unit -- it's extremely easy to read, especially in a moving car or when you glance at it while in the field. The power button controls the level of backlighting -- there are three levels (I usually stick with the second, intermediate level at night) and the timeouts are programmable via the menus. The GPSMAP 175 uses what looks like Futura Condensed for menus and text, and for small type on the maps and the CDI uses what seems to be the same typeface as the revised G45 software. Both are highly legible. For the time, position and speed screens, it uses large numerals, about .25 inches high, very highly readable from several feet away. This is another great feature as far as I am concerned, made possible by the overall size of the display. I had never before used a 12-channel unit and was of course knocked out to see 12 channel positions. In general, I have not seen more than 10 satellites in average use. Like other units, when it sees a satellite it shows hollow signal- strength bars during the acquisition process, the bars filling in solidly when a satellite is acquired. A small display to the left of the skyview shows EPE (estimated position error), DOP (dilution of precision), and battery life, in a fuel-gauge format. The skyview display can be configured either north up or track up, which gives you a great rough compass display if like me you are a signal strength freak. Being able to track many sats simultaneously means that the unit is much more sensitive and precise than the G45. It also means that satellite acquisition is much faster. Typically, it takes less than a minute to acquire 2D position and 3D position follows very shortly (these figures reflect experience in urban areas). If the unit is "hot," acquisition time is generally much less. Occasionally, the unit will sit for from 3 to 5 minutes without acquisition; I believe this is linked to low battery power or perhaps early software bugs. I haven't yet had the experience that is regular to the G45 where you have to reboot in order to "unfreeze" the unit and acquire satellites. I rarely get an EPE of 49 feet (about the best SA allows) but quite often get EPE's in the 60 or 70 foot range, in and around New York City. [EPE does not include the effects of SA]. DOPs of less than 2.0 are common; my lowest DOP is 1.2 so far. The thing to realize about this unit is that high precision is quite regular, allowing you to record good track while walking, for example. I put the GPSMAP 175 and the G45 side by side on the dashboard and found that the 175 always saw more satellites and was consistently more accurate at tracking a route (and less subject to SA error) than the G45. On the other hand, the G45 often displayed lower EPE numbers. Go figure. The second screen (I forget its name) shows track (with a moving compass band), speed over ground, course over ground, altitude (one figure only, without any indication of vertical error -- you have to assume vertical error, and many people may not know about this), and trip mileage. The trip mileage counter is easily resettable and works well, but undercounts by exactly 4 percent (when used in an automobile). Plus, if the unit is powered down, this counter will continue to increment at power up where it was left off, and will not reflect true trip mileage. The position and all displays can be shown in all the usual formats. This unit also permits Maidenhead Grid and Taiwan Grid, in addition to all the others available in the G45. The moving map is quite great. It works at range scales from .125 to 4096 miles, which are controlled by pressing the right or left sides of the "Zoom" button. This has to be seen to be believed, though I imagine that future generations of handheld units will support color LCD displays as well as contain higher-definition maps in firmware. Changing map scales is quick but occasionally slows down for "loading," and it slows down a lot when G-charts are inserted (see below). The internal database contains what amounts to an outline map of the world, but it focuses on coastal areas. Therefore, Houston is displayed, but not San Antonio, and huge areas of the United States appear without any legend other than superimposed latitude and longitude lines. The internal map also does not extend past somewhere around 68 degrees latitude, which means that no polar features appear. The manual shows what parts of the world are omitted, but most places the Western sailor might head are covered. That being said, though, there are a lot of things on this map, and of course the user can superimpose his or her own coordinates. It's a lot of fun to scroll around the map. The basic world map is valid down to the 64 nm scale; then cartography begins to become generalized and eventually disappears. G-charts fill the gap (see below). The map also makes it very easy to initialize the unit, because you can select a point in the map to tell the unit where it is. The map is configured through the menu, and it is possible to control which features appear (at least as far as G-charts are concerned). G-charts are little ROM chips that contain digitized chart information. They come in offshore and inland versions. The offshore ones are geared to the needs of mariners; the inland ones contain Interstate, US and state highways and some county roads, but offer much more detail in the vicinity of lakes, rivers and reservoirs. Garmin will send you a price list on request, but they range from $99.00 (for states and small harbors) to $149.00 (medium-level information) to $395.00 (for electronic charts that incorporate information from as many as 35 government charts). Their cartography department can also send you printouts showing the coverage and paper base maps related to specific electronic charts. The G-charts add a reasonably high level of detail to the moving map, and are good down to 1 nm in some cases, in others not so far. I have not yet taken my unit (just today equipped with a New York State East G-chart, which cost $149.00) on the road, but I expect that it would be a very nice way of tracking road progress. More on this later. G-charts cover very specific areas; I bought New York East, which stops right at the New York border. An example: although the New Jersey side of the Hudson River is contained in the G-chart and in the built-in world map, only half of the George Washington Bridge shows up on the screen -- the half on the New York state side. On the other hand, New York East contains all detail to Syracuse, plus highway information (not water information) for the western half of New York State. The CDI display is three-dimensional, much easier to use and more distinct than the G45. Its attributes are programmable as well. A few other things: you can set "proximity waypoints," which will set off an alarm when you approach them; there is a set of little graphic icons which can associate with specific waypoints on the map, such as telephone, ATM, camping place, dock, etc.; it contains the "tracback" feature found on the G38, which is way cool...you can reverse the track you have taken, and the unit will convert it into a route, defining waypoints automatically. There is a trip and fuel planning module, which I have not yet used; a set of timers, and input-output protocols as usual. The I/O connector is a 13-pin job on the rear of the unit, open and unprotected. I haven't really studied this yet. To sum up: this is a delightful "prosumer" unit that immediately replaced the G45 for me. I can't go back to a single-channel receiver. It's overpriced ($699 at present) and I imagine it will look clunky and dated within two or three years, but I am very pleased with its accuracy, sensitivity, programmability and complement of features. Recommended for those who seek the functionality of an advanced Garmin unit and who are willing to put up with something larger than a G45. WISH LIST: The "Nearest Waypoints" list still contains only 9 waypoints. Another screen of nearest waypoints would be great. "Nearest" is defined as under 116 miles; at 116 miles waypoints disappear off the screen. The unit still stores only 250 waypoints. Other small Garmin units are now holding 500. The speed limit is still somewhere around 100 statute mph. However, in simulator mode, you can jack the unit up to 621 mph! (I assume this is the upper limit of the air units, because it roughly equals 999 kph). Some kind of "battery saver" mode. Right now a set of alkaline batteries (the unit takes 6!) is specified to last 10 hours, and this is expensive! Better design for the battery pack -- it is flimsy and difficult to remove batteries, as another writer has mentioned, and I always feel as if I'm about to break mine. A G-chart showing major highways throughout the United States, or at least one for eastern U.S. and western U.S., for people like me who are drivers rather than mariners. G-charts for wilderness areas, as well. (Who controls G- chart protocol? Is it possible to be a third-party supplier of G-charts?) Some kind of simulated alphanumeric keypad to better enter letters and numbers. I'm sick of using the cursor control to cycle through an alphabet as in my Casio watch. Permission to reprint all or part of this article is granted, but only if writer is credited. Rick Prelinger ---------------------------------------------------------------------- -GPS 20/25/30/31/35 (remote only models)? These units do not have displays. They are for remote use only! Here is a quick chart to separate the remote models: Model Channels board or TracPac ----- -------- ---------------- GPS 20 1/8 board GPS GPS 25 12 board GPS GPS 30/31* 1/8 TracPac GPS 35/36* 12 TracPac *marine mount version of GPS 30 or 35 [Lane Holdcroft] Although it is not made by Garmin, I should also mention the 12 channel Delorme Tripmate for only $150 which includes some nice mapping software for your laptop computer. It also doesn't have a display or buttons. It needs to be "kick started" with a specific NMEA string before it will output data. The GPS is actually made for Delorme by Rockwell. | UNIT P/N COMES WITH GPS20-000 MultiTrac8 sensor board only GPS20-101 GPS20 with GA28 marine ant. and 15' cable GPS20-020 GPS20 with GA27 mag mount ant. and 8' cable GPS20-099 GPS20 Eval Kit* GPS25-000 PhaseTrac12 sensor board only GPS25-010 GPS25 with GA28 GPS25-020 GPS25 with GA27 GPS25-099 GPS25 Eval Kit* GPS30-000 MultiTrac8 and ant. combo GPS30-099 GPS30 Eval Kit* GPS30-100 GPS30 PC Version with DB9 connector GPS31-000 same as above, but with threaded 1" marine ant. GPS35-000 PhaseTrac12 and ant. combo GPS35-099 GPS30 Eval Kit* GPS35-100 GPS35 PC version with DB9 connector * Eval Kits come with GPS engine, antenna with cables & connector, power/data cable with connector, NMEA monitor software & documentation. All Garmin engines come complete with DGPS input capability, PPS timing output and lithium 3V battery on board Further Info PhaseTrac12: 12 parallel channel, phase tracking accuracy in the world's smallest GPS footprint. MultiTrac8: Tracks and uses up to 8 satellites for accurate, reliable GPS data at an incredibly low 1 watt power consumption. With same footprint as PhaseTrac12 and a real time clock, PPS timing and nonvolatile memory right on the board. TracPac: A sure bet on Plug and Play GPS. Combines a GPS engine and antenna in an all weather, low profile housing that's a perfect fit for vehicle and PC applications. Just connect to 10 - 32 volts DC and your data interface, pick the mounting option you need and you're off. Available with choice of PhaseTrac12 or MultiTrac8 engine. Consumes very little power and feature DGPS capability. NMEA 0183 output. PhaseTrac12 MultiTrac8 Architecture 12 parallel channels Patented MultiTrac8 Time to first fix reacquisition < 2 sec < 2 sec warm 15 sec 20 sec cold 45 sec 2 min sky search < 5 min 15 min update rate 1 sec continuous 1 sec cont. Dynamics velocity 999 knots 999 knots acceleration 6 g 3 g jerk 60 m/s^3 20 m/s^3 Datums 102 predefined, 1 user defined Electrical input voltage 5.0V DC +- 5% regulated power consumption 1.1 Watts 0.8 watts (Track Pak's 10-30V DC) 1.4 watts 1.2 watts backup on board 3V lithium (10 year lifetime) sensitivity -166 dBW Timing 1pps 1pps Connectors antenna 50 ohm MCX female connector for active (5V DC @ 15ma) or passive antenna power/data single row, right angle 12 pin male Physical configuration 1 integrated board engine size 1.83"W X 2.75"L X 0.45"H weight 1.1 oz op temp -30 deg C - 80 deg C (remove Li battery for extended usage above 80 deg C) storage temp -40 deg C - 85 deg C Interfaces compatibility 2 RS-232 serial ports data rate User selectable baud rate 1200/2400(tx only)/4800/9600 format NMEA 0183 v.2.0, ASCII inputs initial position, date and time (not required), 2D/3D & earth datum command, RTCM-104 v.2.0 differential outputs position, velocity & time, receiver and satellite status, geometry and error estimates timing output timing output with +- 1 microsecond accuracy The TracPak is an integrated engine/antenna system 2.33"W X 3.80"L X 1.04"H 7.2 oz Connector 50-ohm MCX female 5V DC@15ma for active Operating Temp: -30C->85C Storage Temp: -40C->85C Data Rate 1200,2400,4800,9600 NMEA 0183 v. 2.0 The following info is for the GPS25 only! (The 20 will be real close but I have not cross checked the info) Connector: 1 - Tx2 (Not used) 2 - Rx2 RTCM input 3 - PPS 1us pulse at 1hz. Can drive a 50Ohm load 4 - Tx1 RS-232 compatible Output 5 - Rx1 RS-232 compatible Input (-25 < V <+25V) 6 - Reset supply at least 2.5 V to reset engine 7 - V_Aux External power for battery backup. 50uA. (4 < V < 33) 8 - Gnd 9 - NC 10 - 5V DC Regulated input. +5V +/-5%. 350mA maximum. Must be clean! 11 - NC 12 - NMEA NMEA compatible output (same data as on pin 4) Data Input: Almanac: $GPALM (GPS 25 only) almanac data Initialization: $PGRMI includes position, utc data and time Configuration: $PGRMC includes altitude, datum selection, baud rate Output Select: $PGRMO turns on specific output sentences. Data Input: Almanac: $GPALM (GPS 25 only) almanac data Initialization: $PGRMI includes position, utc data and time Configuration: $PGRMC includes altitude, datum selection, baud rate Output Select: $PGRMO turns on specific output sentences. Data Output: Time have leap seconds accounted for $GPALM: Almanac (GPS 25 only) $GPGGA: Position include time, position, quality, number of satellites used. Horz DOP, Alt, DGPS data age, diff station ID $GPGSA: DOP, active SVs Mode, 2D/3D, Satellites tracked, PDOP, HDOP, VDOP $GPGSV: Sats in View Sv #, elevation, azimuth, S/N $GPRMC: Basic info Time, Position, speed, course, date, magnetic variation. $GPVTG: trak, speed course, mag course, speed in knots, speed in kmh $LCGLL: Loran simulation position, time $LCVTG: Loran tracking simulation course, mag course, speed kts,speed kmh $PGRME: Error Horizontal Error, Vertical Error, Total Error $PGRMF: GPS Fix Week number, gps seconds, date, time, leap seconds, postion, speed (kmh), course, PDOP, Time DOP $PGRMT: Sensor Status Product version, test results( chksum, receiver, stored data, RTC, oscillator,data collection, board temp, board config data. $PGRMV: 3d speed east, north, up, all in m/s Map Datums: There are 104 of them (some are the same) plus one user selectable one if you have your own ideas of how round the earth is. On the $GPGGA NMEA output the message uses: latitude in ddmm.mmmm longitude in dddmm.mmmm On the $LCGLL (Loran position): latitude in ddmm.mm longitude in dddmm.mm [Garmin literature] There is a list server for a group of people buying the 12 channel remote only (no display) Garmin GPS boards at under the name "GPS". There is also a group buy through TAPR for the MultiTrac8 boards. TAPR is the Tucson Amateur Packet Radio group which is promoting packet use with APRS software listed in the web sites section of the FAQ. There is info at: http://www.tapr.org ---------------------------------------------------------------------- -GPS 30/31 description? [The GPS 31 is very similar but apparently has a marine antenna mount.] To those of you who asked what is the Garmin GPS 30: The GPS 30 looks like a PC mouse without buttons. Its dimensions are: 56.4 X 96.3 X 26.7 mm [2.23"W x 3.80"L x 1.04"H]. It has no buttons, no LCD, no battery compartment; just an eight wire cable. [It uses Garmin's MultiTrac8 engine] >From what I've read it works much like the GPS 40 without the human interface (just computer interface) It needs an external power source. It appears to have two wires for power (besides the ground): VIN - Unregulated 10-30VDC 200mA (maximum). Typical operating current is 110mA. VAUX - Optional External Backup Power Connection. This is an optional connection. Internal battery capacity is 180 mA hour. typical current requirement is 65uA @ 5VDC. If used, a 4VDC to 30 VDC power source is required. Luis Lamela ====================================================================== 6.00 DIFFERENTIAL GPS (DGPS): ------------------------ -What is Differential GPS? The US and Canadian governments are setting up Differential GPS (DGPS) stations to transmit correction signals. They are usually broadcast on existing marine beacon frequencies from 283.5 to 325kHz. They are already operational in many areas along the coasts. | In addition to compensating for errors in the position, these correction signals also undo the deliberate degradation of the accuracy (SA) by the U.S. military. Look at the US Coast Guard's web site (under "www/ftp sites" in this FAQ) for locations and status of their differential stations. ---------------------------------------------------------------------- -Garmin's GBR 21 Differential Beacon Receiver and alternatives? When connected to your Garmin GPS, the GBR 21 will increase its accuracy to under 10 meters when within receiving range of Differential Beacon stations on the coasts. This also makes your speed indications accurate to about 1/10 knot, which is great for sailboat racers. Works with DGPS-ready GPS [38, II,] 40, 45, 50, 65, 75, and GPSMAP 210/220 models. Coupler measures 1.6"D x 4.8"H and requires a 4' whip antenna. 30' RG-58 coax included. Receiver box measures 5.2"x3.6"x1.5". Draws 130 mA. One year parts and labor includes water damage. List $799, $499 discounted [West Marine Catalog] I have studied the specifications on the GBR 21 and found that they didn't spec many critical parameters that were specified by other DGPS vendors. That made me nervous about its potential performance. Then I read several reports indicating that the GBR 21 is not very sensitive to weak signals. This would be significant when you are at the edge of the DGPS transmitter's range (typically 60 miles). | The reported explanation is that the GBR 21 DGPS receiver (apparently made by Starlink because it uses the same proprietary NMEA strings) uses an FSK demodulator to decode MSK modulation. A FSK demodulator is much more readily available and makes design and construction costs cheaper but is technically not as good a design as a proper MSK demodulator. | Therefore, I do not recommend Garmin's GBR 21 for areas with weak DGPS beacon signals. Magellan's $500 DGPS unit would be worth a try. Magellan's has good specifications. Of course only the Garmin GBR 21 will automatically tune the frequency of the DGPS receiver from the GPS unit, but that is a small advantage in my opinion. | The DGPS units made by Communication Systems International (CSI) of Calgary, Alberta, Canada are of very high quality. Unfortunately, they cost about 3 times as much as Garmin's! | There are services that transmit correction signals on FM broadcast band subcarriers in most major cities which are not limited to the coasts but you must buy their differential receivers for several hundred dollars and pay a monthly charge. DCI (Differential Corrections Incorporated) and "Accupoint" are most often mentioned. Omnistar is another DGPS service. See the www/ftp sites section for addresses. There are also companies that transmit correction signals via satellite and again you must buy their differential receiver and pay a monthly charge. | ---------------------------------------------------------------------- -Garmin's GBR 21 Differential Beacon Receiver report? Here is a good detailed description and review of the Garmin GBR 21 from Aaron: Garmin GBR 21 (Version 2.0) with Shakespeare Model 173 4' foot Loran C whip antenna **** WHAT YOU GET **** What comes with the GBR 21 exactly? This is rather difficult to determine from the brief catalog information. Here is some clarification. There are 7 things in the box (I ordered mine from West Marine for $499, the Shakespeare 173 was $12): 1) The GBR 21 receiver itself. A black plastic box 5 inches long by 2 3/4 inches wide (3 3/4 inches wide including mounting flanges) by 1 1/2 inches tall. It has a 3/8 inch flange at its 4 corners along the 5 inch side which each have a 1/8 inch mounting hole. On the bottom is the unit model and serial number plate, and six flush head Phillips screws. Removing these screws probably unfastens the bottom of the unit with the mounting flange to expose the electronics inside. I have not felt like taking these screws out and voiding my warranty though. On one of the small (2 3/4" X 1 1/2") sides of the unit are two connectors. A BNC coax antenna connector, same connector as the GPS 45 antenna connector, and a round DIN 7 indexed plug. I do not know whether the DIN connector is a standard type but I suspect that similar to the 4 connector DIN on the back of the GPS 45 it is not quite a standard size or index bump configuration. This DIN connector looks just like the 4 connector one on the back of the GPS 45 except for the fact that it has 7 connectors. The outside diameter of the supplied cable (next item) DIN plug is actually slightly smaller than the plug on the GPS 45 which is somewhat surprising since there are more connectors. The DIN plug on the supplied cable also has a twist lock to securely fasten it to the DIN connector on the GBR 21. The DIN connector on the GBR 21 has an attached snap over plastic cover that will cover the connector when the cable isn't plugged in to prevent dirt from entering the connector (the BNC antenna connector does not have a cover). On the opposite side of the GBR 21 from the two connectors is a label which has an LED light labeled "Signal". This light indicates that the power is on and whether the receiver is actually receiving a DGPS beacon signal. If the light is off, the unit is off. If the light is blinking, the unit is on, but it is not receiving a beacon. If the light is steady on, the unit is on and receiving a beacon. This light is the only status display on the GBR 21 itself. All other status is displayed on the GPS unit (more about this later). NOTE: There is no power switch on the unit, you plug it in, it comes on. If you want an on/off switch you have to supply one and attach it to the wiring harness. 2) A wiring harness/cable that connects to the DIN 7 with a 7 wire cable 7 feet long. The seven wires are: 1) BLACK - Ground 1 2) RED - Power positive: 10-18 volts DC, 130mA (voltage and current from the owners manual). This wire has an in line fuse holder in it, just like the one on the GPS 45 power/data cable, with a AGC/3AG 1.5 amp fuse in it. 3) BLUE - Data Out - This connects to Data In of the GPS unit (the WHITE wire of the GPS 45 power/data cable) 4) BROWN - Data In - This connects to Data Out of the GPS unit (the BROWN wire of the GPS 45 power/data cable) 5) WHITE - Baud in 6) GREEN - Baud out 7) YELLOW - Ground 2 The BAUD In and Out wires are actually "baud rate select". If these wires are shorted together, 9600 baud data rate is selected. With these two wires unconnected, 4800 baud is selected. This option is for non-GARMIN GPS units according to the manual. For GARMIN you want 4800 baud and these wires should simply be left unconnected. There is a description in the manual about why there are 2 ground wires. The BLACK wire is shown in the wiring diagrams as the main ground. From the manual: "Two ground wires are provided on the power/data cable. For reliable communication, it is essential that the GBR 21 and the GPS unit share the same ground. This [YELLOW] ground connection acts as the (current) Return line. You may connect either the YELLOW wire or the BLACK wire from the power/data cable to the ground wire of the GPS unit. NOTE: Some non-GARMIN GPS units may have a separate data line labeled 'RETURN', 'DATA GROUND' or 'DATA -'. If one of these lines exist, connect the YELLOW wire from the power/data cable to it." 3) A Loran C antenna base with 30 feet of RG-58 A/U coax cable coming out of it with a BNC connector on the other end that connects to the BNC coax antenna connector on the GBR 21. A Loran C antenna is not included, just the base to screw one into. The Loran C base is a black plastic tube with a 3/8-inch 24 thread per inch by 1/2 inch deep threaded hole in one end which accepts a standard Loran C antenna base, and a 1-inch 14 thread per inch threaded hole on the other end which is designed to screw onto a standard marine antenna mounting base (there is a wide variety of these available from marine supply stores). This tube has a RG-58U sized hump along the side of the 1-inch marine antenna mount hole which the RG-58 A/U cable comes out of. Additionally, out of this same cable bump, there is a 22 inch length of about 16 gauge black wire with a crimp connector on the end with a 1/4" hole. This is another ground wire. From the manual: "A ground strap is attached to the antenna coupler. For proper operation, the ground strap must be connected to vessel ground. If the coupler is not adequately grounded, the beacon signal may be too weak for the GBR 21 to provide reliable correction data." It is important to hook this ground wire up, at least in my installation. It isn't very important when the signal is strong, but it makes quite a difference when the signal is weak. 4) A 3 inch long rubber boot with a 1/4 inch hole in one end and a 3/4 inch hole in the other. This boot is a weather seal for the top of the Loran C antenna mount (previous item). You slide it over the antenna, and it then snaps over the end of the mount. This puts a weather seal over the connection between the antenna base and the antenna. 5) A DGPS beacon list pamphlet. Looks to be fairly recent. For the United States you are referred to http://www.navcen.uscg.mil/dgps/dgpssts.txt for the most up to date beacon list and status from the US Coast Guard. 6) Owners manual 7) Warranty card **** INSTALLATION **** I hooked the RED, BLACK, BROWN and BLUE wires of the GBR 21 power/data cable to the appropriate wires (see above) on the GPS 45 power/data cable. I left the WHITE, GREEN and YELLOW wires of the GBR 21 power/data cable disconnected. I installed an alligator clip and a bit more wire on the antenna base ground wire and I clip it to a frame screw to get a good antenna base ground. You must then make sure that the I/O setup of your GPS 45 is set to "RTCM/NMEA". Go to the I/O SETUP options and set the top item on the screen to "RTCM/NMEA". The GBR 21 sends RTCM to the GPS unit, which is the data communication protocol that the DGPS beacon transmits, and expects to hear NMEA back. This communications protocol cannot be changed on the GBR 21 side so the GPS 45 has to be set this way. The only option on the GBR 21 side of the communication is the baud rate. You now have to configure the GPS 45 to tell the GBR 21 what DGPS beacon you want it to listen to. The GBR 21 does not know how to auto scan the DGPS beacon frequency range looking for one, you have to tell it which one you want by setting the FREQ and RATE values. I use GPS in my car. I could not find any magnetic base 1-inch marine antenna mounts so I made one by epoxying a white PVC screw flange 1-inch marine antenna base (West Marine, $6) to an Edmunds Scientific 200 lb. power magnet (also got this at West Marine, $40). I stick this on my hood by the AM/FM antenna. The tip of the Loran C antenna is about 1 foot taller than the tip of my AM/FM antenna, so I have to be a little bit careful about watching the overhead clearance (my vehicles are all 4WD and therefore relatively tall). **** NOTES **** By setting RTCM for the Data In on the GPS 45, you have effectively enabled DGPS on the GPS 45. The GPS 45 now expects to hear from a DGPS beacon and will alert you if it isn't there. Thus if you make use of the GPS 45 without the GBR 21 a significant amount of the time, you may want to switch this setting back to one that doesn't enable the DGPS capability (like NONE/NMEA or NMEA/NMEA). The DGPS related alerts I have seen are "No RTCM Input" and "No DGPS Position". The first means the GBR 21 isn't saying anything to the GPS 45, and the second means that no DGPS signals are being received. In practice I have observed that these two alerts usually happen together and you will get alerted twice in succession. According to the GPS 45 manual there is one other alert: "RTCM Input Failed" which means DGPS data was there but has been lost, but I have never seen this one. When in RTCM input mode, the bottom of the I/O Setup menu page on the GPS 45 becomes the DGPS beacon status/setup display which includes a FREQ field where you can set the beacon frequency in kHz, and a RATE field where you set the beacon data rate in BPS (Bits Per Second, effectively the beacon's "baud rate"). There is also a SNR status (signal to noise ratio in dB) which is an indication of signal quality, and a DIST field which shows the distance that the beacon is from your position. The SNR reading seems to be capped at 30dB and any signal strength greater than 30dB will show as 30dB. The DIST field units is coupled to the NAVIGATION SETUP - UNITS setting and will show statute miles, nautical miles, or kilometers depending on that setting. I believe that this is simply a computed value obtained by computing the distance between the beacon lat/long position, which is part of the DGPS beacon data stream, and the GPS 45's lat/long obtained from the GPS satellites. This field may sit as '---' for a while when you first tune a beacon because the DGPS beacons do not seem to transmit their location frequently. The beacons in my area seem to transmit the beacon location data about once every half hour. Additionally the very bottom line of the page shows the basic beacon status, one of: "Tuning", "Receiving", "No Status", "No Data". Tuning means that the GPS 45 is in the process of setting the beacon frequency and rate. Receiving means that the beacon and DGPS data are being received. No Status means that something is not set up properly (this is the status you get if you do something like turn off the GBR 21), or the beacon carrier signal is not being received. No Data means that the beacon carrier signal is being received, but no DGPS data is being received. This can happen in fringe reception situations, or if there is a data transmission or reception problem at the beacon. The FREQ field allows you to enter any number from 000.0 to 999.9, but it will only accept values from 300.0 to 325.0 when you press ENTER (if you make an out of range entry the previous setting is retained). This does not line up exactly with the GBR 21 frequency range which is listed in the manual as 283.5 - 325.0 kHz. The RATE field does not allow you to enter a specific number, instead you hit up and down arrow to select from one of 0, 25, 50, 100 or 200 (I wonder what a data rate of 0 means?). The list of data rates supported by the GBR 21 is 25, 50, 100 and 200. Some of the other GARMIN GPS units apparently have a "DGPS Beacon Log" and will remember the FREQ and RATE settings for the last 4 or 5 DGPS beacons it successfully received so you can switch beacons easily by simply selecting one from the beacon log. The GPS 45 only remembers the last beacon, or if you will, the GPS 45 only has one beacon log entry. When the GPS 45 is receiving a DGPS beacon, the bottom of the signal strength bars on the satellite page will have a letter 'D' if the satellite data is being DGPS corrected. The satellite view at your location may not match the DGPS beacon's and the GPS 45 may be picking up a satellite that the DGPS beacon doesn't receive. In this case the 'D' will not appear on that satellite's signal strength bar. Additionally the status on the upper line of the satellite page will have DIFF added to it when DGPS correction data is being received. So for instance the status will be "3D DIFF" instead of "3D NAV". There is usually some lag here. Once the DGPS data stream reception starts, the satellites will slowly get the 'D's added to them. This is because it takes a while for the GBR 21 to receive the correction data for all of the satellites. The beacon data rates are pretty slow. **** GENERAL COMMENTS **** Consistency. This is the feature you get with DGPS in my application, use with GPS enabled map software (DeLorme Map Expert). What I have observed though is that if I follow a specific route multiple times, my track on the map is much more consistent than it is without DGPS and about to the tune of the expected results, an order of magnitude. DGPS reduces the track variance from around 100 meters to around 10 meters. Since the width of a 2 lane road is approximately 10 meters, this is a substantial improvement for my particular application. I am fortunate that I live in a coastal area, Puget Sound in state of Washington, that has excellent DGPS beacon coverage. I have received two of the beacons in my area up to a range of about 120 statute miles over fairly uneven terrain. I have noticed however that I can totally lose the beacon signal in spots in urban areas. I am not sure whether this is due to terrain factors or electrical interference (like power lines). I have also noticed that I occasionally have excellent beacon reception, but poor GPS satellite reception due to overhead obstructions (like a road lined on both sides with tall trees). I wish the GPS 45 had memory for more than one beacon setting. I have two beacons in my area which I switch between rather frequently and it sure would be nice if the GPS 45 could remember the settings for both of them. Alternately, it would be nice if the GBR 21 could search the beacon frequency range for a beacon and lock onto it automatically. This is not super difficult or expensive radio technology. Almost all AM/FM radios made these days have a "seek" button. You could just put the GBR 21 in this seek mode and leave it that way and it would just "do the right thing" all by itself. Aaron Reynolds ====================================================================== 7.00 FIRMWARE (INTERNAL SOFTWARE): ---------------------------- -90 knot speed limit? New info!: The new GPS 12XL (introduced in Jan 1997) is the first non-aeronautical GPS model from Garmin in a long time to not have the nasty 90 knot limit! This is really encouraging. | There is a firmware speed limit of 90 Knots (Nautical miles/hour), 104 statute MPH, and 167 km/h for all Garmin marine GPS units except the new GPS 12XL. Most of the fields are replaced with dashes or underlines above the speed limit except for the compass and clock. There is no doubt that this is a firmware (software) imposed limit. Contrary to many reports on the internet, the limit is NOT 99 or 100 MPH and it is NOT 99 or 100 knots! | Almost all other civilian GPS receivers have a maximum speed limit of 999 knots and a maximum altitude of 60000 ft to discourage their use on missiles as requested by the US Department of Defense. Actually, this is because GPS's without these limitations are on the Munitions Control List which means distribution is very tightly controlled by the US government. | Garmin's 90 knot speed limit has created a lot of debate in the GPS newsgroup primarily because it used to be totally undocumented by Garmin and is arbitrary. The problem was that people were not forewarned by the spec sheets, the manuals or the box. Since then, Garmin started documenting the 90 knot limit in the manuals and later the spec sheets. Putting it the manuals was letting people know too late, however putting it on the spec sheets was a great help. I feel that it should also be put prominently on the box. | What really got people upset was that they assumed that their GPS unit would work on a plane or in some cases on the German Autobahn highways. This was a reasonable assumption since virtually all other manufacturers units do not have the Garmin 90 knot limit. | This 90 knot speed limit was apparently done to prevent these models from competing with the aviation models that are priced at several hundred dollars more. This is a common marketing technique called "market positioning" or "price positioning". An alternative way to look at it is that aviation unit purchases help to subsidize the costs of the marine models! Garmin's defense is that this was done to reduce their liability costs by preventing their use in aircraft. The other GPS manufacturers don't seem so concerned. The Magellan GPS 2000 (somewhat similar to the GPS 38 but not nearly as full featured) is also available for about $150 and it doesn't have this limitation. Because of the speed limit, some people have bought other manufacturers' GPS units instead. Unfortunately, instead of the warning message "90 knot marketing speed limit exceeded", it states "Poor GPS Coverage" which is simply not true. | The aviation models GPS 90 and 89 are very similar to the GPS 45 except that they have different firmware, a black case, and a couple of buttons are relabeled so Garmin certainly has the capability of making them work above 90 knots. Internally they have more battery backed up memory and could have better shielding. Of course they do not have the 90 knot speed limit and they have some other software features for aviation use such as a database of public airports and navigation aids. See the Garmin GPS 90 and 89 section elsewhere in this FAQ. If you have a GPS 40 or GPS 45 with firmware version 2.41, there is a modification that can be done to break the 90 knot speed limit. It can be done for other versions too but it would require some experimentation. It is rather involved. See Tim Hogard's site in the www/ftp sites section. | Thanks to John M. Lewis for his well documented test with a laptop computer in a plane. His report is included below. Here is a report of the details by John Lewis: I took a GPS 45 into an aircraft, it worked OK up to and below 90.0 KTS. Above 90.0 nautical miles per hour it beeped with "Poor GPS Coverage" and did not display the track, speed, position, or altitude. The time and the "compass card" did display. The track map did not indicate the >90Kts points, nor did the track data download. Upon decreasing speed to 90.0 Kts, even if only for a second, the full display reappeared, with accurate position information. During the speed blackout, the sat status page indicated 8 satellites with nearly full signal strength bars. The GPS 45 was attached to an HP100LX palmtop for data recording. The following is an excerpt edited to pertinent RMC sentences: Garmin GPS 45 V2.32 NMEA V2 RMC sentences ID, UTC-GPS, LAT , LON , KNOTS,Track, Date $GPRMC,231109,A,3030.183,N,08819.149,W,087.2,284.8,140595,,*0E $GPRMC,231111,A,3030.203,N,08819.206,W,086.2,293.9,140595,,*02 $GPRMC,231113,A,3030.229,N,08819.257,W,089.3,300.4,140595,,*04 $GPRMC,231115,V,,,,,,,140595,,*38 $GPRMC,231117,V,,,,,,,140595,,*3A . . $GPRMC,231539,V,,,,,,,140595,,*32 $GPRMC,231541,V,,,,,,,140595,,*3D $GPRMC,231543,A,3032.451,N,08824.848,W,090.0,097.0,140595,,*06 $GPRMC,231545,V,,,,,,,140595,,*39 $GPRMC,231547,V,,,,,,,140595,,*3B . . $GPRMC,231643,V,,,,,,,140595,,*3C $GPRMC,231645,V,,,,,,,140595,,*3A $GPRMC,231648,A,3032.932,N,08824.232,W,086.7,277.8,140595,,*05 $GPRMC,231650,A,3032.915,N,08824.287,W,081.2,256.0,140595,,*0E Reconfiguring the 45 for display in Statute MPH, the display changed to dashes at speeds in excess of 104 MPH. When configured for Metric, the device becomes useless above 167 K/H. The ability to instantly relock and display correct data upon reducing speed to 90.0 Kts, as well as the ability to display correct heading via the compass card indicates a software induced blanking, not a hardware limitation. There may exist a hardware limitation at speeds in excess of 110 Kts, this test flight did not exceed 110 Kts IAS. John M Lewis ---------------------------------------------------------------------- -GPS 45/40 firmware versions? These versions do not apply to any other Garmin products except the 40 & 45. The firmware is believed to be identical between the 2 products except that different model numbers are displayed on power up ("45" vs. "40"). Here are some versions and their differences that have been mentioned in the newsgroup. Most other differences are not known outside of Garmin. V2.02 4/94 Early release of GPS 45 V2.04 1994 ... V2.20 1994 ... V2.24 1994 ... V2.31 V2.32 Shipped for many months V2.40 5/95 New feature: Fuel Gauge gone when connected to external power V2.41 6/95 Some units have simulator random power down problem (minor)++ V2.42 7/95 Simulator random power down problem partially fixed V2.43 9/95 Simulator random power down problem fully fixed [V2.43 was last shipped 7/1996, after that the GPS 45 used the GPS 38 firmware and was renamed the GPS 45XL. This is the last firmware version of the GPS 40.] The above dates are approximate within about 1 month. ++Simulator mode is a mode which simulates satellite signal acquisition, presumably when you are not outside and want to practice with the unit. You can still program the unit indoors (or wherever you are that you can't lock onto the satellites) using "normal mode" instead, however in normal mode the unit will automatically shut down after 15 minutes of not finding enough satellites (to conserve the batteries). If you wanted to update your firmware, you could have the unit serviced at Garmin's $149 flat rate fee for repairs. It is not a trivial operation. See the section "Internal electrical hardware" for the details of what is done for the EPROM replacement. I have seen the simulator bug in V2.41 of the software. Some reports indicate that it does not affect all units with V2.41 firmware. If a unit has the bug, when you are in simulator mode after an apparently random amount of time (sometimes immediately), the unit turns itself off. You simply turn it back on or use normal mode and turn it back on every 15 minutes. This is not a serious problem. I have not heard of any serious bugs in past versions of the GPS 45/40 firmware so it is very, very likely NOT worth upgrading. It is fortunate for us that Garmin is continually upgrading their firmware. Many companies don't. ---------------------------------------------------------------------- -What are the undocumented modes for the GPS 45/40/38/90/89/120/II/12XL? Most of these work on most other Garmin units that are not mentioned above. | Globe spin rate and direction: Go to the map display. Then press the OFF button for 1-2 seconds. The globe will still be on the screen and you can change the speed with the up/down buttons and the direction of rotation with the right/left buttons. Press any other button to return to normal mode. Test screen: Hold down ENTER while pressing on the POWER button. Invokes button test screen and displays labeled: SNR Signal to Noise Ratio DRIFT of FREQ below FREQ apparently this is a 16 MHz internal clock TEMP degrees Celsius BATTERY voltage in hundredths of Volts EXTERNAL external power connector voltage in hundredths of Volts TIME Universal Coordinated Time without local offset Press LEFT or RIGHT arrows to adjust contrast. Press ENTER 2 times to get an all black screen, press ENTER again for cool exploding rectangles on the display. Press ENTER again to exit this mode. Hold down OFF button to exit test screen. Also turns beep on if you had it off! Full reset and memory clear: Hold down MARK while pressing on the POWER button (CLEARS MEMORY!!!). DO NOT TRY THIS UNLESS YOU ARE WILLING TO LOSE ALL SAVED INFO!!!!!!!!!! Waypoints, Track, Routes and more will all be gone. I would not do this unless my GPS unit was having serious problems (and then only as a last resort attempt to fix it before sending it in for repair)! It returns all settings to initial factory defaults. Diagnostics mode: To get into this mode, quickly after turning on the power (while the globe is still spinning), press all 4 arrows one at a time (in any order). On some of the newer units (such as the GPS 12XL), you have to old down each button longer than is necessary for the old GPS 45 to successfully get into diagnostics mode. | 2 or 3 digit numbers are added to many screens. Reportedly they are the process stack depth. The signal strength bars are initially hollow. They become solid apparently when some specific data has been downloaded from the satellite. The number in the bottom right corner of the satellite screen is the HDOP (Horizontal Dilution of Precision) which is a unitless quantity indicating the quality of the fix based on the geometry of the received satellites. | The internal temperature is is added to the position screen to the right of the time. The units (C or F) will change depending on whether you selected metric or statute in your setup. | A "DIAG" (GPS 45/40) or "D" (GPS 45XL/38/II/12XL) option for diagnostics is added at the bottom of the menu screen. The following is displayed on the diagnostics screen: Battery voltage in hundredths of volts. Elapsed time (can be zeroed by pressing ENTER, except for GPS 12XL). Screen can be paused by pressing MARK. Looks like there is a lot of internal software debugging info. AutoLocate mode: | If PAGE is pressed during power-up, the GPS45 powers-up in the AUTOLOCATE (Sky Search) mode. The I/O set-up is also reset to the GRMN/GRMN protocol. The AUTOLOCATE mode can be cancelled by manually setting either NORMAL or BATTERYSAVE from the operating menu, before switching off. If power is cycled before cancelling AUTOLOCATE, this mode is still active at the next power-up, or until satellite acquisition is achieved. Derek Hare | GPS 40 mode [may only work with older firmware versions]: I just found an interesting feature of my GPS45 (v2.32). Pressing the center of the thumbwheel switch (engaging all four) upon powerup results in the welcome screen changing to "Welcome to the Garmin GPS 40", with the same software version mentioned as in the 45 announcement. [Editor was not able to duplicate w/ V2.41 firmware] Michael J. Klein ---------------------------------------------------------------------- -What are some undocumented modes for the GPS 75? + switch on and press ENTER: display & receiver osc.-selftest + switch on and press the '0'-button: go to Auto- Locate-Mode + switch on and press CLR: completely destroy the RAM contents (clock, almanac, route, settings) Sebastian Birnbach ---------------------------------------------------------------------- -Why is internal temperature available? In some electronic circuits, it is useful to measure the internal temperature so that it can be used to compensate for changes in components over temperature. As the unit warms up, this internal temperature will generally be warmer than the ambient (surrounding) temperature. The internal temperature measurement is not intended for use as a thermometer to measure the air temperature (although it would probably work immediately after the unit is turned on before it warms up). I would speculate that the temperature is used to monitor the drift of the 16 MHz clock since apparently the frequency drift info is displayed on one of the diagnostic screens above. There are two different modes on the GPS 45/40/38 that allow you to read the internal temperature. See the previous "Diagnostics mode" and "Test screen" sections above for details. ---------------------------------------------------------------------- -VMG error? Garmin has apparently implemented the VMG (Velocity Made Good) differently than most other GPS manufacturers on the GPS 45 and GPS 75. It appears that maybe it was fixed in the (newer versions at least) GPS 38 but I have seen conflicting reports which are probably due to variations in firmware versions. The 45 [and 75] VMG calculation shows you your speed along a course from your starting point to your destination. This gives you misleading (IMHO) readings. (It still gives you a positive VMG after you pass your destination and are getting further away from it.) The 38 displays a correct (IMHO) VMG from your current position to your destination and ignores your starting point. Randall P Devol The 75 [and 45] only knows where you told it you wanted to go when it was selected. It assumes you want to go to the 'active' waypoint from the point where you were when you pressed the 'GOTO' button'. If you wish to change this starting position just press 'GOTO' again and select the desired waypoint to 'GOTO'. Now VMG will be the new speed made good to the waypoint from the current position. vic fraenckel ---------------------------------------------------------------------- -Garmin NMEA 0183 data sentences? | See the NMEA FAQ on Peter Bennett's site listed under www/ftp sites in this document which gives the old 45/40 and new 45XL/38 sequences. | GPS 45/40 info: 0183 version 1.5 (Approved sentences BWC, GLL, RMB, RMC, XTE, VTG, WPL; Proprietary sentences PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control)). 0183 version 2.0 (Approved sentences [GGA], GLL, GSA, GSV, RMB, RMC, RTE, WPL; Proprietary sentences PGRME (estimated error), PGRMM (map datum), PGRMZ (altitude), PSLIB (DGPS beacon remote control). For the GPS 38 and 45XL, the following sentences were added: NMEA 0183 V1.5 BOD NMEA 0183 V2.0 WPL and PSLIB] --------------------- Here is an interesting report from Derek Hare about the uploading of waypoint data using the NMEA protocol: | I have also successfully managed to UPLOAD waypoint data to the GPS45 using the NMEA PROTOCOL. Providing that the data is formatted correctly using the $GPWPL sentence, bearing in mind the six character limit on Waypoint Names imposed by the GPS45, waypoint data can be successfully be transferred without risk of corruption. Using the Garmin protocol is not easy, and can produce significant corruption, whilst the NMEA protocol is fully syntax and error checked, and *very* easy for a novice to implement. In its simplest form, each Waypoint can be defined in a single $GPWPL sentence. Many sentences can be assembled in a single text file, one sentence per-line. The resultant file can then be sent directly using plain ASCII to the GPS45. If you're really keen, the optional checksum may be calculated and added to each $GPWPL line. Providing that space exists in the GPS45 memory (250 waypoints max), new waypoints will be created for each Waypoint name that does not currently exist; pre-existing Waypoints are updated with fresh data (ie, overwritten). Trials have also shown that the GPS45 is very insensitive to NMEA Talker ID; everything that I have tried works without complaint (obviously checksums change). If an error is detected during upload, the GPS45 will either ignore the data, or sound an alarm whilst displaying "An invalid Waypoint has been uploaded" in the message page. Derek Hare ====================================================================== 8.00 BATTERY/POWER: -------------- -How is power selected between the internal batteries and the external supply? This differs between the 40/38 and the 45. The 45 switches more completely to the supply with the highest voltage. The 40/38 does a slower crossover from one supply to the other as the voltage of one exceeds the voltage of the other, and will draw part of its operating current from a current-limited external supply such as a solar panel, even if the current-limited supply cannot supply the total power needs of the GPS 40/38. The remaining current which the solar panel cannot supply is supplied by the internal batteries. Larry James (http://www.csn.net/~lwjames) If neither is high enough, the unit will shut off to allow the memory to be maintained. ---------------------------------------------------------------------- -What voltages do the GPS 45 fuel gauge correspond to? I hooked up a GPS45 to a variable supply in the shop and found the following in testing the battery monitor display. DC supplied thru battery compartment [V2.32] Full reading ~5.65v 3/4 ~5.3v 1/2 ~5.00v 1/4 ~4.6v Empty ~4.25v low battery alarm, unit turns off Readings did not exactly repeat and there appeared to be some hysteresis, hence the tilde. Unit transitioned smoothly between external dc and internal batteries when external power was cycled (unit did not lose sat lock). David Wells There are variations between units so the above info may not apply directly to your unit! For example, my unit shuts off between 3.7 and 4.0 V when powered by internal batteries. However, when externally powered, it only goes down to 6.25 V. Keep this in mind if you are using an external battery pack! You can easily calibrate your own unit by going into diag mode or the test screen as explained under the FIRMWARE section and just compare the battery voltage with the fuel gauge at various battery levels. It is easy to see what your actual battery life is in hours and minutes by using the elapsed timer in the "Diag mode" and simply zeroing it when you change batteries. ---------------------------------------------------------------------- -Current consumption of a GPS 45 at different external supply input voltages? This is from a GPS 45 unit with V2.41 firmware and internal batteries removed: (There are manufacturing variations between units and this does NOT apply to a GPS 40/38) Normal Mode (as opposed to Battery Saver mode) Simulator Mode uses half as much current POWER POWER V in OFF ON ---- --- -- 6.25 V 1.0 mA unit turned itself off! 7 V 1.1 mA 144-166 mA 8 V 1.3 mA 120-138 mA 10 V 1.8 mA 80-100 mA GPS 45 only, GPS 40/38 might be damaged! 12 V 2.3 mA 68-84 mA GPS 45 only, GPS 40/38 might be damaged! 14 V 2.8 mA 62-78 mA GPS 45 only, GPS 40/38 might be damaged! 16 V 3.3 mA 62-76 mA GPS 45 only, GPS 40/38 might be damaged! 24 V 5.2 mA 64-80 mA GPS 45 only, GPS 40/38 might be damaged! 32 V 7.1 mA 64-80 mA GPS 45 only, GPS 40/38 might be damaged! There is no advantage to a supply with more than about 14 Volts as the extra voltage will just be converted to heat. It has been reported that up to an external supply voltage of about 8.5V, the batteries are being discharged. Note that Garmin now specifies the unit for 10 Volts MINIMUM. | Also (on the GPS 45 at least), there is a big difference between the battery input and the external power input circuitry. ---------------------------------------------------------------------- -How does BatterySave mode work? According to Garmin's Tech Support Department- These are a couple of the things the saver does: 1. Stops the unit from trying to re-lock if it loses the birds. 2. Cycles the receiver off and on periodically if you are motionless. Ralph Fowler Garmin technical support also claims that there is no disadvantage to Battery Saver mode but many people have observed that the ability to hold lock on satellites is poorer under weak signal conditions in Battery Saver mode. Most people feel that the BatterySave mode offers only a modest battery life improvement in general use. If you have a strong signal, it probably does not hurt to leave it in Battery Saver mode. If you change modes, then the unit loses all satellites and must reacquire them (although it happens quickly). Also, as is mentioned in the manual, when you have trouble getting the receiver to lock on the satellites, if you turn the unit off and then on again it often performs much better. [Lane A. Holdcroft] The RF circuitry draws considerable power. In normal mode it is on continuously. In battery saver mode, after a lock is established and the necessary data downloaded from the required number of satellites, the RF circuitry is turned off for short periods, then back on. If the user's velocity vector is constant during the off period, then when it comes back on, the satellite signals will be right where the receiver expects them to be (in time). When the receiver verifies that, it can go back to sleep again for another short period, saving the batteries. If the signals are not where expected, if the velocity change is small, the receiver can quickly find them by searching either side of the expected time delay. Obviously no change in velocity can be detected while the RF circuitry is off. The conclusion is: If you are going at a nearly steady velocity under a clear sky, use battery saver mode. If you are under trees with marginal signals, or want the fastest possible response to velocity and direction change, use normal mode. Larry James (http://www.csn.net/~lwjames) Here is yet another informed person's explanation: The battery saver mode cycles the receiver portion of the GPS on for one second and off for two (then repeats) to conserve power. The CPU portion of the GPS is on continuously and interpolates speed/position during the off cycle. If the GPS has a hard time keeping up with speed/heading changes (i.e. a "high dynamics" situation) then Battery Save will automatically be overridden in favor of Normal mode operation. It will revert back to Battery Save operation (again automatically) once speed/heading readings stabilize. ---------------------------------------------------------------------- -GPS 38 batteries too tight? | The battery compartments on some GPS 38 units were too small for many popular batteries. Some batteries (particularly some NiCd batteries and batteries that have built-in battery testers) are slightly larger than normal and may fit tightly in the GPS 38. They could be very difficult to get out if you force them in! I usually got mine out by whacking the bottom of my GPS 38 into the palm of my hand. Some people have had to go to elaborate means. The new "Power Check" Duracell alkaline batteries (and maybe even the new EverReady's with the built-in battery tester) have been singled out as being much larger than normal and are much more likely to get stuck. | Apparently Garmin made the battery compartment too small. They claim that the batteries are too big. However, many very, very popular brands of batteries are getting stuck. Reportedly this problem has been fixed on newer GPS 38 units. The 38 case was changed in January 1997 so that the same case could be used for the GPS 12XL. Therefore it should be fixed. Some people have used sandpaper or an emory board to file down the ridges that prevent the batteries from fitting. I read somewhere that Garmin gave a special reaming tool to some dealers to fix the problem. | The GPS 45 battery compartment has not had this problem. | ---------------------------------------------------------------------- -Batteries? Alkaline Batteries: Alkaline batteries work great and are available from some discount stores (such as Costco or Sam's Club) for $10 for 40 batteries. Recharging single use batteries is not recommended by the battery manufacturers. I tried charging some single use Rayovac alkaline batteries in my Renewal charger and found that the batteries got very hot. Therefore I agree with the manufacturers recommendations and do NOT recommend charging single use batteries and consider it to be a potential safety hazard. I remember some alkaline chargers from about 10 years ago that seemed to work fairly well until people also tested another set of batteries that weren't charged and they did just as well (because of the rebound effect that batteries have after a rest). | Renewals: Rayovac Renewal (tm) rechargeable alkaline batteries work well in the GPS 45/40/38 units. They are only rated for about 25 recharges (compared with approximately 300-1000 recharges for NiCd batteries) but have a slower self discharge rate. Also, the capacity decreases about 2% per full discharge/ recharge cycle. They also have less capacity than normal alkaline batteries. Also the fuel gauge reads more accurately than with NiCd's. The chargers are about $12 US and the 4 AA batteries cost about $7 US. Unlike NiCd batteries, Renewal batteries will last much longer if you charge them often and don't let them discharge all the way down. They are available at large discount stores such as Walmart, K-mart, & Target in the US. I like them much less now that mine are wearing out due to too many charge/discharge cycles (as documented by the manufacturer). | NiCd: Nickel Cadmium batteries are much cheaper long term than standard alkaline batteries or even Renewals particularly if you use your unit a real lot. Unfortunately the battery life is about 5 hours per charge (600mA batteries) instead of about 7 hours for Renewals or 10-12 hours for standard alkaline batteries (assuming that you are not in BatterySave mode). Unfortunately, the fuel gauge gives a less accurate state of charge for NiCd batteries because they have a more constant voltage over their discharge cycle instead of the gradually decreasing voltage of alkaline. Carry a spare set of NiCd batteries with you because the fuel gauge can drop off very quickly! The so called memory effect of NiCd batteries (properly called "voltage depression") is considered by many knowledgeable people to be negligible with current technology high quality (Japanese) batteries. However, this is a very controversial issue. I have never seen the so-called memory effect and I have used dozens of NiCd batteries over the last 10 years. NiCd damage is usually due to overcharging. Another cause of problems is when there are a lot of batteries in series (typically 5 or more) and during discharge one of them is allowed to reverse its polarity. As a result that battery is damaged. | Lithium Batteries (not rechargeable): AA (1.5V) Lithium batteries are available and last MUCH longer than any other batteries of the same size. They perform much better in cold temperatures than other battery types. They are more expensive and are not usually rechargeable. | [Lane Holdcroft] There's been a lot of discussion about rechargeable alkaline vs. single use alkalines. While surfing around for stuff for and about my Garmin GPS-38, I stumbled on a gif-graph of battery life for a GPS-45. "Empty" Meter Turn off 1.1v/cell ~0.875v/cell Lithium 17.5 hr 19 hr Alkaline 13 19 Renewal 6 11 Carbon-Zinc 4.5 6.5 NiCd 5.5 5.5 David Kunz | ---------------------------------------------------------------------- -Other battery/external power options? Of course an optional cord could be used if you have some other DC power available at the appropriate voltage such as in a car or boat. Do not forget the fuse! Garmin uses 1/4 Amp for the GPS 45, and 1 Amp for the GPS 38/40. | Some people have also hooked an optional power cord to an external battery pack that could supply power for days of use. Select your battery pack voltage carefully! Usually, you do not want most types of batteries to be discharged below 0.9 V /cell. See a previous section for info on current consumption at different voltages (for the GPS 45 only). Again, do not forget the fuse. For a GPS 40/38 (which has an input voltage of 5-8 V), 5 D-cell alkaline batteries would work out well (5 x 1.5V = 7.5V). For a GPS 40/38 with NiCd's, 5 or 6 cells should work. (6 cells might be too high a voltage with other types of batteries). Dave Martindale reported that on the GPS 38/40, if less than about 6.5V is supplied externally, then the internal batteries are slowly being drained even though the fuel gauge may indicate that all of the power is being supplied externally. The higher the voltage of the internal batteries and the lower the external supply voltage, the more likely that the internal batteries will become partially discharged. Garmin's GPS 38/40 cigar lighter converter supplies 8.0VDC. Apparently it won't hurt if it is a few tenths of a volt over 8.0V. Therefore, I would suggest using an 8V input as provided by a 7808 8V 3 terminal regulator (with input and output capacitors as specified in the data books). Some typical part numbers are National Semiconductor LM7808, Motorola MC7808, and Texas Instruments uA7808. ---------------------------------------------------------------------- -How long is memory conserved without batteries? I am told that older versions of the 40/45 used a capacitive circuit to maintain memory while the batteries were changed. As a rule of thumb, the batteries should not be left out for more than one hour. While in the field, if the batteries go kaput leave them in the unit. There's still more than enough juice to maintain the memory until fresh batteries can be installed. >From the Owner's Manual and Reference, GPS45 Personal Navigator, Software Version 2.20 or above, 1994, Garmin International, part number 190-00070-00 Rev. B, page 47, "Never store your GPS45 without batteries. A built in capacitor will save almanac and waypoint data while you are changing batteries, but will only save data for a period of time (a few hours). If you are storing the unit for the season, put in a fresh set of alkaline batteries to help prevent the loss of stored data." DUDLEY Newer versions (since about mid/late 1995), have an internal rechargeable lithium battery than maintains the memory when batteries are temporarily removed. These batteries should last the life of the unit. I believe the GPS 90 has always had the lithium battery. ---------------------------------------------------------------------- -Does the serial I/O consume much more power when it is enabled? I have measured [the current consumption] with the 45, 50, and 75 and could see no change measuring down to +/- 1mA. So if it does it is negligible. Tom Miller I tested the GPS 40 and it too does the same. davew ---------------------------------------------------------------------- -What is the minimum external supply voltage for the GPS 45/45XL? | Originally the GPS 45 was specified to operate between 5V DC to 40V DC. I noticed that mine turned off at below 6.2 V. It also appeared that the power supply appeared to be optimized for about 12V. The GPS 90 (presumably identical power supply) was specified from 8V - 40V. Since then somebody else pointed out that between 5 and 8.5V, current is being drawn from the internal batteries even though the external power enunciator may be off. The newer GPS 45XL spec sheets state that the voltage range is 10V-40V. The specs were apparently changed to make them more accurate. I am not aware that the input power circuit design has changed at all. Therefore in conclusion, the minimum recommended voltage is now 10V although it will operate lower but possibly drain the internal batteries or shut off if the voltage is too low. (Lane Holdcroft) | ---------------------------------------------------------------------- -What is the external voltage range for the GPS 12XL | 10-40VDC. Garmin made an error in their early GPS 12XL spec sheets and manual and they inadvertently used the GPS 40 voltage specs. | ====================================================================== 9.00 SERIAL/POWER INTERFACE: ---------------------- -External serial/power connector alternatives? Garmin uses a non-standard 4 pin (for GPS 45/II/12XL) round connector. A center pin is added for the GPS 40/38. I personally recommend buying the cable with the correct connector from Garmin. Garmin sells a data/power cable for the GPS 45/II/12XL and a different one for the GPS 38/40. They are both about $30 list. However, some dealers sell them for much less. The GPS 38/40 data cable will work in a GPS 45/II/12XL, however I do not recommend it because there is a possibility that a GPS 38/40 might be powered from it in the future and be damaged by the excessive voltage. | You can strip back the outer sleeve and gain access to the power wire also. However, don't input more than 8VDC to a GPS 38 or 40 or damage may occur! I personally feel that building your own cable is risky because of the possibility of mis-indexing the connector which could damage the unit. Also, there is a risk of intermittent operation due to the mismatch between the pin and socket size if you do not replace the sockets. I have experienced this. Some people have substituted a 5 or 8 socket DIN connector for the GPS 40/38 or a 4 or 7 socket DIN connector for the GPS 45. There are several socket arrangements for the DIN connectors (even with the same number of sockets!). You should plug any unused holes (epoxy works) and if you are using the DIN sockets (not as reliable), you need to bend the contacts in to improve the reliability of the contact with the smaller pins of the GPS 45/40. I have had contact problems using this arrangement initially and over time. I do not recommend it! See the other alternatives below. You also should wrap the connector with tape and/or heat shrink tubing to bring it out to the correct diameter. If you do not do a good job on this last step, you risk damaging your unit due to mis-indexing the connector. Here is a much better design for a home built cable using Radio Shack parts that addresses the contact problems above: The connector for the Garmin GPS 45/40 has been the subject of a number of inquiries since I last posted my description of how to make one. It is easy and inexpensive. Here are instructions: 1. Remove sockets from RS-274-001 4-pin mike connector and drill out holes (1/8"). Drill 5/64" hole for center post (GPS 40). Wrap with (2 turns) tape (for snugger fit), and cut out tape at key. [heat shrink works well too] 2. Solder (or crimp) D-Sub socket-pins [RS-276-1538] on cable wires. Put plastic (heat-shrink works) tubing on socket-pins and insert them in connector holes. Fix them in place temporarily with pieces of plastic tubing pushed in from ends so as to press socket-pins outward (bolt- circle of GPS pins is larger than that of connector holes). 3. Insert connector into GPS body and push socket-pins down onto GPS pins. Apply epoxy resin (ca. 3 drops) to inner ends of socket- pins (too much could run too far down and ooze out end - the tubing that was pushed into the holes helps prevent this). 4. After epoxy is set, tighten cable clamp to cable, wire cable to computer/power interfaces, and enjoy. Rane L. Curl N8REG Larry Berg of Purple Computing has molded a bunch of Garmin 45/40/38 connectors at a very good price. It is nice of him to help out. See his site in the www/ftp sites section. There are at least several optional power cables available from Garmin. They are serial data only, power only, and both. You must supply the appropriate connectors for the computer end of the cable that has both power and data. There is even a Garmin to Garmin transfer cable so that you can upload the stored data from one unit to another. See the accessories list elsewhere in this FAQ. Several people have reported that if you buy the data cable, you can cut the insulation near the connector end and the red power wire is there. See the next section for the pin out. ---------------------------------------------------------------------- -How do I interface the GPS 45/40/38/II/12XL to an IBM-PC compatible computer? The easiest way by far is to order Garmin's " 40/45 PC Interface Cable", Garmin order number "4041". It is about $30 retail. For older computers with a DB-25 serial port, you may also need the appropriate DE-9 to DB-25 adapter. | Garmin DB-25 DE-9 Function color* socket socket -------- ------ ----- ---- data in white 2 3 data out brown 3 2 ground black 7 5 power in red N/A N/A (for ext. power only, do not forget to add the fuse!) *Garmin 45 manual, Appendix F I strongly recommend using Garmin's wire colors (as also stated in the manual) to minimize confusion. Or for those that like diagrams: 25-pin -or- 9-pin female female brown>--------------->o3---------------o2 white<--------------- FILENAME". In addition to supporting WGS84 by default, they now support uploading and downloading from any of the 100+ Garmin supported datums. | G7TO2x.ZIP (Ron Henderson ) converts GarDown7 download files to Street Atlas 3 format, or vice versa, and converts either format to formats compatible with PROJ.EXE, NAD2NAD.EXE, or UTMS.EXE. This program can also communicate directly with a Garmin receiver using the Garmin protocol, and has been tested on a HP200LX. The exact name changes with the version. EASYNAV COMMUNICATIONS GARLINK (formerly GARMIN) by Peter Aigner (shareware, $40): A Windows program written in Visual BASIC to upload and download waypoints, track info, and routes. Since Version A.01.06 it has a several month trial period. You may need to send mail to the author of the program to get a pass code to enable it for the free trial period until you support it. When sending E-mail from the internet to the author at a Compuserve address, as usual you have to replace the commas with dots. It also downloads some interesting info such as such as the current satellite locations. | WAYPOINT+ (BHildebrand) Runs on Win95 and WinNT. Waypoint+ is a program to download and upload waypoints, routes and tracks from the Garmin 45 and a PC running Windows 95 or Windows NT. It can save the data as ASCII, or create a file that can be read by DeLorme Street Atlas. See http://ourworld.compuserve.com/homepages/rimmer/waypoint.htm | FUGAWI Windows moving map program. Costs around $100. There is a free demo. Here is their summary: Fugawi, a Windows moving map program, will upload and download tracks, waypoints and routes to your Garmin. It is also a complete moving map navigation system. Demo is at http://www.fugawi.com | GARMAP.ZIP provides an interface between Mapinfo Desktop Mapping Software and a Garmin GPS receiver, using the proprietary Garmin/Garmin protocol. Do not forget you have to set your GPS 45/40/38 "I/O SETUP" to "GRMN/GRMN HOST" or the above programs will not work in Garmin mode. GMN_DXF1.ZIP converts the data downloaded by GARDOWN into a .dxf file for import into AutoCad or other drawing programs that read this format. WINGPS by Jos Verbeek (freeware): A Windows program written in Visual BASIC that talks NMEA 0183 but also has some Garmin options. It uses the Garmin data files generated by the utility GARMIN by Peter Aigner. GPS-Pro Map Available at www.gpspro.com. It can upload/download Garmin, Magellan, and Eagle/Lowrance, plus show NMEA real-time tracking on a variety of raster and vector backgrounds ---------------------------------------------------------------------- -What MS-DOS/Win software is available that communicates using NMEA 183 format? JNAV82.ZIP by Joel C. Koch (shareware $50): A MS-DOS program that displays and logs NMEA 0183 data. GPSNMEA by Dr.W.Pieper (Public Domain): A MS-DOS program that displays and logs NMEA 0183 data. APRS - Amateur Packet Reporting System (shareware $25+): There is also a DOS version and a Windows version as well as a Macintosh version (MacAPRS). This is mapping software written by Radio Amateurs that also supports GPS and live tracking. GARMIN65.NMEA Prepared by Peter Bennett An annotated listing of NMEA 183 sentences (including Garmin unique sentences) sent by a Garmin GPS 65. The GPS 45/40/38's implementation of NMEA 183 is very similar. Manning Navcomp offers RASTRAC, a WINDOWS/NT/'95/ system that supports popular GPS hardware and moving maps starting at $195. The ADV and MX version supports PCMCIA cards, multimedia advisories and GIF/JPEG/etc. A free version of the software is available for download at http://www.navcomp.com/navcomp/. (del nichols) VISTA GPS map software (by RMS Technology) | Moving map program. You can also scan the maps in yourself. I have heard from several sources that it is pretty good. about $200 See http://www.navtechgps.com for info. LOGNAV 3.0 (shareware) Versions for Win 3.x, 95, and NT as well as the Psion S3A see http://www.cyber-espace.com/lognav/indexen.html GPSS (details unknown??) IBIS (details unknown??) You could use almost any terminal program and just log the MMEA 183 data of course. Kermit, Procomm and the MS-Windows Terminal are a few of the most common terminal emulator programs for PC's. ---------------------------------------------------------------------- -Other MS-DOS software? Here is a bunch of info about software. I have never seen any of their products but I have heard some positive reports and their prices are generally very low. FOR GARMIN MODE ONLY (GPSXFER): GPSXFER is utility which can Download Track logs, Download Waypoints, Upload Waypoints and Combine Files for assembly of map or WayPoint logging. GPSXFER communicates via the serial port to the GPS in use at 9600 bps. The protocol used supports only Garmin GPS's with the following model numbers, GPS-40, GPS-50, GPS-45, GPS-65, GPS-75, GPS-85, GPS-90, GPS-95. GPSXFER allows the GPS to do all the work in the field by collecting track logs and Waypoints, then once back to a computer those records can be retrieved from the GPS by using GPSXFER. The file format that GPSXFER creates can be used with "GPM-PRO" (also available from Cole Enterprises) mapping software to view trips and create maps. GPSXFER runs from DOS. This allows all laptop and Palmtop computers to run it. It supports both Color and Black and White Monitors. The only requirements are DOS 5.0 or later, and 400K of available RAM. This program works great on the HP 200 Palmtop. Price for GPSXFER is $30.00 U.S. NMEA MODE: The following is a list of S/W products which might be useful for the Garmin GPS's. All of these products work with the NMEA string coming out of the GPS, so this is ideal for the GPS engines. GPSDASH is designed to receive data transmitted by a GPS over a serial port and use it to derive, Speed, Max Speed (Bar graph and numeric), Altitude, Max Altitude,Trip and Total Distance, Latitude and Longitude, Heading (Compass dial and numeric), Number of Satellites used and D.O.P. (Dilution of Precision). Other information displayed in GPSDASH but not derived from the GPS is, Elapsed Time, Current Time, Remaining memory, Log file name , size and divider rate. Distances will be retained from exit of program to re-entry of program so that long time logging can be maintained. GPS's used should transmit NMEA 0183 ver 2.0, although earlier versions can be used but will not contain all of the data. Data rates handled are 4800bps and 9600bps. This program can be run stand alone or as an auxiliary screen from "GPM-PRO" mapping software also available from Cole Enterprises. GPSDASH will automatically initialize the GARMIN GPS-10/20/25/30/31/35/36 series of receivers. GPSDASH runs from DOS. This allows all laptop and Palmtop computers to run it. It supports both Color and Black and White Monitors. The only requirements are DOS 5.0 or later, and 400K of available RAM. This program works great on the HP 200 Palmtop. Price for GPSDASH is $30.00 U.S. GSPDASH and GPSXFER bought together are $50.00. GPM-PRO is designed to receive data transmitted by a GPS receiver over a serial port and use it to create real time maps or read in files to view from past trips. The views can be scaled to any size such that overlays can be made for placement on any map. Waypoint entry is extensive which allows the user to create custom overlays for use with the real time mapping or post viewing. During real time mapping other statistics transmitted by the GPS are displayed such as , Speed, Max Speed, Altitude, Max Altitude,Trip and Total Distance, Latitude and Longitude, Heading, Number of Satellites used and D.O.P. (Dilution of Precision). It is a very useful GIS tool. Custom data dictionaries are easily constructed by the user allowing almost unlimited hot key selections. [much detailed info deleted] Price for GPM-PRO and Utilities is $250.00 U.S. GPSDASH and GPSXFER can be purchased for $10.00 each if bought at the same time as GPM-PRO. A complete GPS Tracker kit is available, including a GPS, Palmtop PC, and necessary interfacing cables etc. Call for details and quotes on the Tracker kit and for Custom software/hardware requirements. GPM-SAT is a satellite viewing program that will operate stand alone or in conjunction with GPM-PRO. It shows a sky view of satellites available and over a period of time, history tracks will develop showing the satellite movement. Signal-Noise bars are shown for the individual satellites. When used in conjunction with GPM-PRO, will continue the track log being recorded. Visa/Mastercard Accepted. Or send Check to: Cole Enterprises 614 Cedar Hill RD NE Albuquerque NM 87122-1814 Sales (505) 856-7402 (505) 856-7446 FAX [Software Quantity Discounts are available for 2 or more copies.] GPM-PRO package includes GPM-SAT $250.00 GPM basic pkg includes GPM-SAT 70.00 GPM-SAT alone single copy 30.00 GPM-SAT if bought with either GPSDASH or GPSXFER 10.00 GPSDASH 30.00 GPSXFER 30.00 GPSDASH and GPSXFER together 50.00 GPSDASH if purchased with GPM basic or GPM-PRO 10.00 GPSXFER if purchased with GPM basic or GPM-PRO 10.00 All orders are plus shipping. ---------------------------------------------------------------------- -GPS www/ftp sites? Caution, these links are constantly changing! GARMIN SPECIFIC SITES: Garmin finally got their site up and running: http://www.garmin.com | Tim Hogard has Garmin electrical hardware and Garmin's proprietary protocol information on his Web site: http://www.abnormal.com Larry James supports the MacGPS_45 software and sells Garmin stuff at reasonable prices: http://www.csn.net/~lwjames Here is a mirror site for MacGPS_45: ftp://ftp.hawaii.edu/mirrors/info-mac/sci/ filename starts with larrys-mac-gps Larry Berg of Purple Computing has homebrew Garmin 45/40/38 connectors: http://home.cdsnet.net/~purple/projects/g45contr/g45_idx.htm GPS SELLERS: http://www.lowe.co.uk/ http://www.csn.net/~lwjames ?? GPS MANUFACTURERS: New Garmin home page: | http://www.garmin.com Eagle home page: http://www.uni.net/eagle/ http://www.eaglegps.com/ Lowrance home page: http://www.lowrance.com Magellan home page: | http://www.magellangps.com GENERAL GPS INFORMATION: Peter Bennett has an excellent ftp site and WWW page which have most of the freeware/shareware programs, an excellent NMEA FAQ and a general GPS FAQ: ftp://sundae.triumf.ca/pub/peter/index.html http://vancouver-webpages.com/peter/index.html ftp://ftp-i2.informatik.rwth-aachen.de/pub/arnd/GPS/peter/index.html Intro to GPS Applications - Archive: http://www.he.net/~jbeadles/gps/index.htm Introduction to GPS Applications Web Page: http://galaxy.einet.net/editors/john-beadles/introgps.htm You can find some basic GPS information links here: http://www.inmet.com/~pwt Good general GPS info: http://www.utexas.edu/depts/grg/gcraft/notes/gps/gps.html GPSy demo site, a Macintosh program for NMEA strings: | http://www.yale.edu/~nakamura/gps/gpsy.html Comparison chart of most GPS handhelds and a bunch of GPS links: http://www.eskimo.com/~archer/gps.html Links to the Totally Accurate Clock and the group purhase of Garmin's boards: http://www.tapr.org/ | List of benchmarks in the US: | http://www.ngs.noaa.gov/ CommSystems Intermountain sells GPS stuff and accessories: | http://www.commsysin.com DGPS SITES: CSI makes very good DGPS equipment for the US/Canadian Coast Guard broadcasts: http://www.csi-dgps.com/ DCI sells DGPS signals: http://www.dgps.com Omnistar also sells DGPS signals: http://www.omnistar.com US GOVERNMENT GPS SITES: US Coast Guard: http://www.navcen.uscg.mil/ GPS signal spec info: http://www.navcen.uscg.mil/gps/reports/sigspec/sigspec.htm | US Geodetic Survey: http://www.usgs.gov/ MAPPING SOFTWARE: Fugawi makes GPS map software: http://www.fugawi.com DeLorme Mapping's home page: http://www.delorme.com/ Precision Mapping home page: http://www.justsoftworks.com APRS (Automatic Packet Reporting System) has a MS-DOS version and a Windows version as well as a Macintosh version (MacAPRS) that support GPS and mapping. The shareware is available from: ftp to "ftp.tapr.org" cd to "/tapr/SIG/aprssig/upload/" or web address: ftp://ftp.tapr.org/tapr/SIG/aprssig/upload/ OTHER: MIT's scatter plots for GPS w/ SA & GLONASS (Russia's version w/o SA): http://satnav.atc.ll.mit.edu GPS World magazine (the printed trade publication for professional GPS users): http://www.gpsworld.com http://www.advanstar.com/GEO/GPS/ Some great free programs for converting between coordinate systems, calculating distances, and transferring points to and from maps: ftp://ftp.wizvax.net/pub/personal/victorf World Lat/Lon database by city: http://www.indo.com/distance/ US Lat/Lon database by city: http://tiger2.census.gov/places.html US Lat/Lon by address: | http://www.geocode.com/eagle.html-ssi | The very latest version of this FAQ is available on my www and ftp sites (I also send it to Peter Bennett's site): http://www.eskimo.com/~klah/index.html (preferred) or ftp://ftp.eskimo.com/u/k/klah/index.html or ftp to "ftp.eskimo.com", cd to "/u/k/klah" ---------------------------------------------------------------------- -Digital maps with lat/lon? Prices and versions could easily be out of date! | There are numerous errors on these maps such as missing and misnamed streets. This is not usually the fault of the company selling the software but of the map data that is provided to them by the government. But all in all the data is generally decent. | DeLorme's Map Expert (Windows). Excellent program, but expensive. Lat/Lon at cursor. Selectable Lat/Lon grid overlay. $300 discounted DeLorme's "GPS Link" for Map Expert above Offers real time track data by reading NMEA 183 output. $200 discounted (The previous 2 programs are available in the "GPS MapKit" for about $500) Map'N'Go by DeLorme mapping ($50) A Windows street level mapping program that can talk to GPS's using both NMEA and Garmin's protocol. DeLorme's Street Atlas USA (Windows). DeLorme's Street Atlas USA (Macintosh). V3.0 added Lat/Lon support, unlike V2.0. Not nearly as powerful as DeLorme's Map Expert but has the most important stuff. Generally considered pretty good for the price. It uses the WGS-84 datum. 800-452-5931 $80 list price, discounted $45. Precision Mapping discounted to about $40. Just Softworks Inc. (708) 257-7616 A little clunky but has many features. Somebody claimed that there is also a "lite" version that does NOT support Lat/Lon. The Precision Mapping GPS Edition was released in July 1996. There is also a Complete GPS Kit for $339. http:\\www.justsoftworks.com Microsoft Automap Streets MS-Windows based. Turn on lat/lon by selecting Tools,Track. Lat/Lon is displayed for mouse cursor only. There is a new add-on software available that does support the Garmin 45/40/38 family (among others). List price recently dropped to about $55 | For Worldwide Lat/Lon: You can get Encarta World 97 Atlas (not Encarta Encyclopedia). It has a tool called location sensor. This allows you to get the lat/long of any part of the world. Ronald Barnstone ====================================================================== 11.00 ANTENNAS: --------- -What is the GPS 40/38/12XL internal antenna? It is a "patch" antenna design. The same antenna is also used on the optional remote antennas GA 27 (GPS 40) and GA 26 (GPS 45) except that the remote antennas are amplified. ---------------------------------------------------------------------- -How is the GPS 45/90/89/II antenna internally constructed? Thanks to a friend whose GPS 45 antenna case split open, we were able to examine the antenna construction. It is a quad-helix circular polarized antenna. It basically looks like a double sided flexible circuit board rolled into about a 1/2 inch diameter cylinder. It has 4 spiral elements that look like the stripes on a candy cane. It is definitely a a passive (non-amplified) antenna. However, it does work very well. Several people have reported that when the plastic protective antenna case is removed, it doesn't work as well due to detuning the antenna. Someone has X-rayed their GPS 45 antenna and scanned the image. Look at the files grm45ant.gif and grm45ant.inf on Peter Bennett's www/ftp site. Replacement antennas cost $100 from Garmin which is a little expensive in my opinion. | ---------------------------------------------------------------------- -How well does the internal antenna work inside a car? You can use a GPS unit on the dash of your car with the built-in antenna but the roof of the car shields between 1/3 to 2/3 of the satellites depending entirely on your windshield slope, dash slope, and antenna mounting design (swivel 45 vs. fixed 38 style). I found that my 38 and 12XL do not work out well in some cars. I can either see the GPS display or the GPS can see the satellites, but not both at the same time! I did not have this problem with my old GPS 45. I believe the GPS 45 antenna is superior because of its ability to swivel. | There are some tinted windows (which may also be used in a sunroof) and some electric window defoggers that use a conductive coating between the layers of glass that block the satellite signals. Of course they will shield the signals from the antenna. Newer General Motors cars and some european cars are known to use conductive windshields. Of course you can get much better reception with an external antenna on the roof. ---------------------------------------------------------------------- -What are the remote antenna options? GPS 45/40: There are several basic approaches to external antennas: 1) Obtain an external antenna. If the coax is going to be longer than several meters, then the antenna should be amplified to overcome the signal losses in the coax. The GPS 45 and 40 supply 5 V to the coax connector. 2) Use the existing non-amplified antenna and insert a short piece of coaxial cable between the connectors. With this approach, you only have to pay for a coaxial cable extension and perhaps a gender changer and/or 90 degree elbow. The satellite signals are severely attenuated by coaxial cable at the civilian GPS frequency of about 1.5 GHz. If the original (non-amplified) antenna is used, the cable length should usually be kept less than about 3 meters. Garmin sells a couple of external antennas that work very well. There is a wide range of mounting options including suction cups, magnetic, flange, and trunk lid mounts. See the accessories section of the FAQ for details. Many people have reported that the external antennas work MUCH better than the built in antennas when they are walking through trees. This is because most most external antennas are amplified and apparently there is not enough amplification with the built-in antennas. Also your body blocks some of the satellites. If you are walking, you could mount the external antenna to your hat or to a pipe coming out of a backpack. Garmin sold a non-amplified remote antenna for the GPS 45 for about $40. I have not heard any reports about it yet. It sounds like a good low cost solution for use with your car or when walking as used above. MODEL CONN. ANTENNA OPTION ----- ----- -------------- II BNC GA-26, GA-28 12XL MCX GA-27 38 none none 40 MCX GA-27 45 BNC GA-26, GA-28 75 BNC GA-26, GA-28 170 MCX GA-27 175 MCX GA-27 | ---------------------------------------------------------------------- -GPS 45 antenna extension cables? You can buy a SHORT coax extension and mount the antenna on the inside of your windshield or sunroof. Radio Shack sells 6 foot coax RG-58/U extensions with suction cup mounts (RS 20-022) or a window edge mount (RS 20-023) for about $15. You will need a 90 degree elbow (RS 278-116a) for the window edge mount and it can be useful for the suction cup mount too. However there is a risk of antenna theft or possibly the antenna flopping down or falling off. Also, the coax can get pinched in the window or alternatively there will be a noisy air leak. You can also just buy a piece of coax but you will also need a BNC gender changer and a way to mount it. The 6 ft of RG-58/U (a very lossy coax at these frequencies) drops the signal strength a little on the display. Garmin offers a 6 ft antenna extension for the GPS 45 (Garmin 5519). It has a screw/suction cup mount. It costs about $40. ---------------------------------------------------------------------- -Can I make my own external antenna? Yes. There have been several postings that reference the articles below. A GPS antenna is difficult to design for many reasons: The signal is very weak. The frequency is quite high (1.5 GHz). Antenna tuning is very difficult because of the expensive equipment required. A hemispherical radiation pattern is desired. Right hand circular polarization is desired. In the ham radio magazine "QST" (October 1995) there is a good article on how to simply construct a "patch" style GPS antenna using easy to obtain materials. The file "gpspatch.zip" on Peter's ftp site also has lots of information. It is relatively easy to construct and the materials are inexpensive! You may want to use an easier to solder material than aluminum if you don't have copper foil tape or appropriate solder and a large iron. Some people have found the signals to be weaker but they all have worked. Several people reported that it doesn't work as well for satellites near the horizon. However, it is still the best antenna design I have seen so far for home construction. The "Satellite Experimenter's Handbook" (by Martin R. Davidoff, published by the American Radio Relay League) has a quadrifilar helix antenna. It could be tough for many people to get the very small coaxial hardline that is needed. The dimensions are very also critical. This particular antenna apparently presents a dead short to the +5V supply on the GPS unit's external coax connection if connected normally. Therefore, the antenna likely needs to have a small decoupling capacitor in series with the center wire of the coax to prevent blowing the internal fuse ($150 service charge!). When my antenna is complete I'll post more. If the coax is longer than several meters, you will likely need an amplifier to overcome losses in the feedline. Several people have suggested the MMIC MAR-6 or the newer EAR-3 amplifiers (all sold by MiniCircuits) which look like an excellent choice because of their low voltage, low current, good gain at 1.5 GHz, and their ease in impedance matching. They also only cost about $2 in quantities. HP makes some suitable amplifiers also. | Apparently, Ma/Com also makes a GPS preamplifier IC ($8) which is designed for this application (but much harder to obtain). Lowe Electronics in England is selling an antenna that looks like the Trimble Minature OEM antenna but with a BNC adapter. Their address is in the www/ftp sites section. | ---------------------------------------------------------------------- -What is the Trimble OEM antenna? | The Trimble "Minature OEM Antenna" is the cheapest amplified antenna I have seen and it is of very high quality. It has a built in magnetic mount and is very compact. Unfortunately it draws about 26mA of current compared to 15 mA for Garmin's external antenna. Because of the additional current, the battery voltage going to the antenna is only about 4.5V when the GPS is powered by batteries (but it really depends on the battery voltage). It is an excellent antenna but it cuts down on battery life. Therefore, instead I recommend the Garmin antenna. Although the list price is $160, the Garmin antennas are only $90 from James Associates (I have no association with them). The Trimble antenna has an SMB connector so you have to have to convert it to your connector type. The GPS 45 uses a BNC type connector. Adapters are available for about $75 to about $30 and are somewhat difficult to find! If you want to go to a BNC, it is easier to just cut the cable near the SMB connector and use Radio Shack BNC part number 278-126 as a replacement. It works well and looks very nice. You don't even have to solder. However, from an Electrical Engineer's standpoint, it is a very non-ideal connector but it works quite well in this application. The price has increased to about $75 from both the following suppliers: Paccomm http://www.paccomm.com Tampa, FL (800-486-7388) Tri-M Systems http://www.tri-m.com British Columbia, Canada phone: (604) 527-1100 toll free: (800) 665-5600 fax: (604) 527-1110 Here is a nice report: Ok, here are the specs for everyone for the Trimble Miniature OEM GPS Antenna (also called a Mini-mag on occasion): OEM Product Bulletin 95-016 NEW Miniature OEM GPS Antenna Part #: 28367-00 Size: 47mm X 40mm X 13.3mm Weight: 180g Mount: Magnetic Cable length: 5 Meters Cable conn. type: SMB Weatherproof 25dB LNA (gain) Will operate WITH or WITHOUT a ground plane. requires +5V DC to operate (GPS receiver must supply 5V on the center pin of the antenna connector) **LNA(Low Noise Amplifier) specs: Freq range: 1,575.42MHz +/- 1.023Mhz Gain: 27dB min. Noise figure: 1.5dB Max (+25'C +/- 5'C) 2.1dB Max (+80'C) Out of band rejection: fo=1,575.42 Mhz fo +/- 20Mhz 7dB Min fo +/- 30Mhz 12dB Min Output Impedance: 50 Ohms Output VSWR: 2.0 Max ***Total specs (thru Antenna,LNA,Cable and Connector) Frequency Range: 1,575.42 Mhz +/- 1.023 Mhz Gain: 23dBi Min (on a 65mm X 65mm ground plane, -40'C to 80'C) Noise figure: 1.6dB max (+23'C) 2.3dB max (+80'C) Output impedance: 50 Ohms VSWR: 2.0 Max. Hope that clears-up any misinformation about this antenna. Better to get the specs from the 'horses mouth' than his. . . . . . . !!! (Chris Findley) ---------------------------------------------------------------------- -What is the loss for different coaxial cables? Based upon information in the spec sheets for coaxial cable, I think RG-6/U (75 ohm) coax is the most attractive from a standpoint of loss at 1.5 GHz and flexibility but it is not 50 ohms. Another poster independently came to the same conclusion. The loss would not be much of an issue if the run was less than several meters. The losses due to a impedance mismatch would likely be less significant than the attenuation of the cable (at least for longer runs). Even Garmin uses RG-59/U coax (75 ohm) on one of their external antennas. loss per 100 feet RG-__/U Z OD(in.) dB (@1GHz) SORTED BY IMPEDANCE & LOSS: 218 50 .880 4.5 219 50 .880 4.5 217 50 .555 6 8 52 .415 8.8 212 50 .336 8.8 213 50 .412 8.8 215 50 .412 8.8 214 50 .432 9 223 50 .216 17 55 53 .206 17 58 50 .200 20 (solid center?) 58A 50 .200 23 (stranded center?) 58C 50 .200 23 174 50 .105 >>20 6A 75 .274 11.2 *best tradeoff between size, loss, & impedance? 59 75 .250 14 62 93 .250 9 71 93 .250 9 63 125 .415 6.5 Here is another chart from another source showing the maximum cable lengths. Note that the cable loss specs are different probably because there are minor variations in the coax type. Max cable length for a non-amplified antenna is about 8-9 feet using RG59 and 6 feet using RG58. Other cable types will differ. Here's a cable loss chart for a Garmin amplified antenna: CABLE TYPE MAXIMUM LENGTH RATING AT 1GHz RG211A/228A 217 ft 4.5 db/100' RG217/224/293/14 126 3.8 RG8/215/216 87 9 RG6/142 71 11 RG59 64 11.5 RG58 40 20 RG88 26 30 ---------------------------------------------------------------------- -What is the GPS 40/12XL antenna connector? It is called an MCX connector. Garmin also sells a short cable that converts from a BNC to MCX connector. This allows the use of BNC cabled antennas on the GPS 40/12XL. | One primary manufacturer of these connectors is: Huber & Suhner Inc. One Allen Martin Drive P.O. Box 400 Essex, VT 05451 One of the representatives (who sent me their 1" catalog of RF connectors) is: C.W. Swift & Associates, Inc. 15216 Burbank Blvd, Suite 300 Van Nuys, CA 91411 (818) 989-1133 (818) 989-4784 (Fax) (800) "MICROWAVE" -> 642-7692 Keith Huie I talked to C.W. Swift & Associates today and the Garmin GPS 40 antenna connector (MCX) has the part number 16MCX-50-2-5C/133 (this is the right-angle version [for RG-316 cable]). It costs $5.01 qty. 1 and they have a minimum order of $50. They will take orders less than $50 but will charge $5 for handling. Tim Tsai They also have cable assemblies with an MCX on one end and either F, BNC, or TNC on the other. Cable can be either RG-179 (75 ohm) or RG-316 (50 ohm). These cables are small diameter and not real low loss. I would suggest getting a 1 ft cable assy and then adding on a length of a much lower loss cable such as Times Microwave LM-240 or even LM-400 to go the rest of the distance. Jerry Lucha ====================================================================== 12.00 MISCELLANEOUS: -------------- -GPS mounting options? Garmin sells a very nice swivel clamp bracket (the "4518") for $45 (list). It used to be included w/ the GPS unit but they lowered the price and removed it and a cable. There are other companies that make GPS mounts, ham radio mounts, and cellular phone mounts for less money but they are not as nice as Garmin's. Velcro (tm) adhesive strips (the generic name is "hook and loop" fasteners) work out well for use in many locations and are very inexpensive and are available at Radio Shack and some sewing supply stores. ---------------------------------------------------------------------- -Waterproofness: The new GPS 12XL has a new case that is supposed to be more waterproof. This same case is used on the new 38's and presumably GPS 45XL's. It sounds like Garmin is trying to improve the waterproofness of their units. | The GPS 45/40 was called "waterproof" by Garmin. I noticed that the newer spec sheets say instead that they are "ultrasonically sealed". It sounds like most units were initially waterproof, but many are not after a while. More than a few people have reported leaks resulting in fogging in which the unit was submerged. This was often due to use in a kayak. In 1995 I got the same story from Garmin Technical Support as several other people. "We guarantee it to be waterproof [for one year] but don't recommend submerging it." I would NOT submerge the units although they should be able to take splashed water. Garmin has been good about supporting their one year warranty. The GPS 45 is filled with dry nitrogen to prevent the screen from fogging due to condensation. The battery compartment is intentionally not waterproof (to allow venting for the batteries) and it would seem to be a good idea to dry out the compartment and batteries after exposure to water. If you don't want to take any chances and expect to submerge it, I would buy a marine radio waterproof plastic bag at well stocked marine supply stores. They usually have a huge Zip-Lock (tm) type seal which keeps the water out pretty well. You could also use an inexpensive "ziploc freezer bag" from your local grocery store. They are not as thick as the $20 bags but thicker than the sandwich bags. If you want to feel better taking your GPS near water, several companies make waterproof bags. One of the better ones is manufactured by Aquaman, aptly called the Aqua Pac. Call AccessorEase at 800-413-9009, they go for about $20. They make two sizes. One fits the GPS 95 and the Lowrance AccuNav and other big GPS receivers, they stock it as the BD43. For the smaller ones like the 45 etc., the BD 45 works like a champ. I don't know about everyone else, but I think it's pretty cheap insurance. (TomZMan) If you were to open the case, you would break the ultrasonically welded seal and it would leak water. It is not intended to be resealable. It has been suggested that you should grease the GPS 45 antenna connector before exposing it to salt water to help prevent corrosion. I have heard reports of significant corrosion after the BNC connector was splashed with salt water. The GPS 45 antenna case seal between the two halves can easily split break. ---------------------------------------------------------------------- -Cases? The case that now comes with the unit is strictly a carrying case and the unit is not operable with it because it does not have a clear window. West Marine has a blue (formerly yellow) neoprene rubber "floating" padded carrying case with a somewhat clear plastic window (for use of the buttons and display) and its name printed on it for $12. The West Marine part# is 253791. It does not keep water away from the GPS unit. It looks like it was designed for the GPS 40. The GPS 45 is a little tight around the antenna connector where the antenna hangs off so you have to careful how you swing the antenna. It is a good investment in my opinion. However, the display is not as easy to read through the flexible plastic window. You could also use a small cellular phone case with a clear plastic window. | ---------------------------------------------------------------------- -Garmin 45/40/38 wish list? Here is a list of suggestions for Garmin that people have suggested and which I think would have broad appeal in my order of priority: Remove the 90 knot speed limit. Add distance traveled function (not straight line distance between 2 points). Perhaps select end points by waypoints or on track log. This data is already in the track log. [this was included in the new GPS 38 and GPS 45XL] Save altitude to waypoints and track log. Add a display mode in which the velocity and heading in degrees are in HUGE numbers for easier viewing from a distance. Add selectable stationary position averaging feature for more accuracy such as offered by Trimble (Acu-Lock) and some Magellans. Add selectable longer averaging time for velocity. Currently it seems about 5 seconds? Velocity is currently of little value for sailboats due to SA. Allow editing for renaming of existing waypoints and creation of new waypoints. Usually the new name is similar to an existing name and it is frustrating to have to start from scratch instead of starting with the existing names. Use flash ROM so the unit's software could be easily upgraded through the serial port. Unfortunately it would be more expensive. Add "over and up" feature to automatically handle map interpolation (such as offered by Trimble). Adjustable proximity alarms would be handy. Remove the limitation of only showing the 9 closest waypoints on the track log map. This is very annoying and seems totally unnecessary! It would also be nice to have more than one page of "closest waypoints". Remove the limitation of only showing waypoints within a certain distance of the current location on the track log map or extend the distance limit beyond between 100 and 200 nautical miles. | ---------------------------------------------------------------------- -Can I use my GPS unit in a plane? You must first have the pilot's permission. It is possible that the GPS unit could interfere with the navigation/communication systems. This does not usually happen, but it could. This is true for many electronics, especially if they involve a radio receiver (which is part of a GPS unit). It is also against most airline policies to allow the use of most personal electronic devices during takeoff and landing (and some extend beyond that). In the US, Federal Aviation Regulation (FAR) 91.21 addresses this. | Of course, the GPS 45/40/38 will not work above 90 knots anyway so it would only be useful on slow planes or gliders. ---------------------------------------------------------------------- -Internal electrical hardware? Tom Miller and Tim Hogard bravely took apart their GPS 45/40 units and they described the circuit board. Check out Tim Hogard's home page as listed in the www/ftp sites section elsewhere in the FAQ for more information. Here are some of the most interesting identified parts: Manuf. Part No # pins Function INTEL TS80L188EB13 80 CMOS 80188EB cpu ATMEL AT27LV020 32 3.3V 256k x 8 (2Mbit) EPROM DALLAS DS1202 8 serial time IC & small NVRAM MITS M5M5256CVP 28 32K x 8 SRAM PHILIPS SA626DK 20 FM IF amp,det,limtr,mixer,osc GARMIN ? custom IC #1 GARMIN ? custom IC #2? The Intel 80L188EB microcontroller is a derivative of the Intel 8088 microprocessor used in the original IBM-PC. The GPS 45/40/38/90/89 firmware is not in flash memory. However, the GPS 12XL Apparently DOES use flash. Flash memory would be of interest because flash would likely be re-programmable through the serial port (without opening the case and removing the part from the board). | The EPROM (which contains the firmware) is a "One Time Programmable" (really an EPROM without a window) surface mount unsocketed part. It must be removed for a firmware upgrade. Unfortunately it is DEEPLY BURIED. The fact that the firmware is in EPROM, explains why it costs so much for a firmware upgrade (not that an upgrade is necessary). It would require breaking open the case, desoldering the surface mount EPROM, resoldering the new one, testing the unit, replacing the case, ultrasonically welding the case, filling the case with dry nitrogen and resealing it. ---------------------------------------------------------------------- -Why is the GPS 45/40/38/90/89 firmware not in a socket? There are several reasons why manufacturers generally are reluctant to use sockets: 1) Reliability. There is a much less reliable connection with sockets. 2) Cost. Sockets (other than for DIP IC's) are usually expensive. 3) Clearance. Sockets require more space above the circuit board. The advantages are that sockets make firmware upgrades and troubleshooting easier. ---------------------------------------------------------------------- -Can I receive GPS signals through my house? Sometimes you can receive a signal indoors. A metal roof, metal siding, or metal foil vapor barrier would block most of the signal. Of course, even if there isn't any metal blocking your signal, other construction materials such as wood or roofing materials will attenuate the signal to a lesser degree and entirely block it if there is enough between your antenna and the satellites. ---------------------------------------------------------------------- -For how long will a particular track interval collect data? I just got my new Garmin 45 last Friday and played with it over the weekend at my deer lease. I kept wondering where I should set the logging to so I put together the following table. It may help others. Garmin 40/45/38 Capabilities based on 768 Points Sample Rate Sec Min Hr Day 1 per sec 768 12.8 1 per 5 sec 3840 64 1.1 1 per 10 sec 7680 128 2.1 1 per 15 sec 11520 192 3.2 1 per 20 sec 15360 256 4.3 1 per 30 sec 23040 384 6.4 1 per 45 sec 34560 576 9.6 1 per min 46080 768 12.8 1 per 1.5 mn 69120 1152 19.2 1 per 2 min 92160 1536 25.6 1.1 1 per 2.5 min 115200 1920 32.0 1.3 1 per 3 min 138240 2304 38.4 1.6 1 per 5 min 230400 3840 64.0 2.7 1 per 10 min 460800 7680 128.0 5.3 1 per 15 min 691200 11520 192.0 8.0 1 per 20 min 921600 15360 256.0 10.7 1 per 30 min 1382400 23040 384.0 16.0 1 per hour 2764800 46080 768.0 32.0 (Robert C. White) ---------------------------------------------------------------------- -Where can I purchase a unit? Garmin should be able to locate a local dealer. Address and phone numbers (since mid-1996): Garmin International 1200 East 151 St. Olathe, Kansas 66062 Toll free: (800) 800-1020 Non Toll free: (913) 397-8200 Existing Fax: (913) 599-2103 New Fax: (913) 397-8282 Many marine supply stores carry the GPS 45XL and 38. Here are some most often mentioned sources for Garmin products: Bass Pro Shops 800-227-7776 or 417-863-2499 Boater's World 800-826-2628 or 206-575-1920? Cabela's 800-237-4444 or 308-234-5555 | E&B Marine(WM?) 800-533-5007 or 908-819-7400 West Marine 800-538-0775 or 408-728-2700 Larry James of James Associates 303-530-9014 [As well as being a Garmin dealer and the maintainer of MacGPS, Larry is very knowledgeable about Garmin units and often provides information to the GPS newsgroup.] Repeating: I am not affiliated with Garmin or any of their retailers. This document is not in any way endorsed by Garmin International. I am only a satisfied customer. Lane A. Holdcroft KE7UT