I decided that I wanted a cheap low cost DGPS reciever so my solution is to build one.
The early ideas involved using a FGPA or the Skiper Chip by Pacific Crest but that seems oever complicated and the Skiper Chip hasn't been seen.
One of my posts
Subject: Homebrew DGPS PLL Newsgroups: sci.geo.satellite-navSo I need a cheap DGPS reciever so I'm going to have to build my own.
I've started looking into RF design. There is a resaons I stay digital... Either way, I've found two chips that I think will generate the needed 284.0->325.0khz that is needed. The first choice is the National Semiconductor LMX1501A which is about $7.32 from digikey. With a crystal that would build the basics of the synthesizer for under $10 in homebrew quantites. The other choice of a chip is the Motorola MC145173 which is a much better choice but harder for the hobbist to find. I also checked into basic stamps at the local electronics shop and they do look like a reasonable solution to the 50/200 baud reframer and they can be found easily. I would personlay prefer the 6811 but thouse are a bit too hard to find in small numbers.
If anyone develops anything worthwile, I've got a web and ftp server that can be used to share info that shouldn't go in the newsgroup.
Peter's FTP site (The GPS archive):
WE7U's GPS Links (including the DGPS FAQ)
Low cost PIC-Programmer for PIC16C84 etc:
DGPS Receiver Project (also see FTP link near bottom of page):
'Software' based DGPS decoder software (from the above FTP link):
Adventures in GPS antenna construction:
Homemade Helical GPS Antenna:
Sam's GPS raw data pages (Build a OEM GPS):
And an amazing well organized site with tons of GPS related links that I
sure will be helpful -- Sam Wormley's Navstar (GPS) Resources: