Posted: 6/21/2010 11:08:52 AM EDT
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Instead of creating a hijack in another thread I thought I would ask a few questions about building a homebrew GPS system.
1. What do I need to interface with the GPS satellite sytem? Is it a package deal of antenna and reciever? 2. Does free software exist that would interface with the above and allow it to run on a laptop in a vehicle? I am sure someone is knowledgeable on this subject and I hope you don't mind me picking your brains. I got into ham because technology fascinates me, and I think the ability to assemble a home brew-ish GPS system is awesome. I've been looking around and I can't find a definitive source on this subject, so if you can point me in the right direction that is always good too. I fully realize I can buy a Tom-Tom for $100, but its just not at the level of awesome that tinkering and building my own would be. Thanks in advance |
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Look for a Holux USB GPS Puck on ebay. That has the antenna and receiver built it and they are pretty cheap. Most of them also have a connector to use an external active GPS antenna if you ever need it. Then it's just a matter of software. I'm currently using a Holux GPSlim236 bluetooth puck. ETA: http://cgi.ebay.com/New-Holux-USB-Mouse-GPS-Receiver-GR-213-SiRF-III-/230475078842?cmd=ViewItem&pt=GPS_Devices&hash=item35a9629cba |
| I got a Motorola GPS board out of an early GM car with on-star. There used to be a kit from Tuscon packet radio ( http://www.tapr.org/gps_vpib.html ) for integrating with the onstar board, but they quit making it since GPS units got so cheap. I built mine in small project box, and wired it to the vehicle power, remote antenna etc. The project had a very simple RS232 serial interface DB9 connector. You had to fire it up the first time, connect a PC to it via the serial and send it a few commands using a terminal com program to get it started. Then it just ran, spewing NMEA sentences out the serial connection. I used this kit to drive my Kenwood D700 APRS for several years, Now, nearly any GPS unit will burp out NMEA...but back then it was kinda unique. |
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Thou shalt begin with Sparkfun. And you'll need some degree of CPU power too. May I suggest FEZ, Arduino or Blueboard?
ETA: All the GPS modules that Sparkfun sells (as far as I know) output NMEA which you can route to your TNC (through a level converter if necessary). But you get homebrew bonus points if you put the data through a microcontroller and do something interesting with it first. 
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Bleeding over from the packet thread above.......
http://www.garydion.com/projects/whereavr/ How would that be for cool points?  Arduino based SOFTWARE TNC?
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I bought one if these http://www.amazon.com/Garmin-18x-LVC-Navigator-Unit/dp/B0016O3T7A/ref=sr_1_1?ie=UTF8&s=electronics&qid=1277266183&sr=8-1 Wired it to USB for power and then serial for the output. I'm not using it for GPS coords but rather its PPS (pulse per second) signal as a precise method to sync my server clock on my home network which all my systems in my house then sync to. -Foxxz |