GPS circuit diagram - click for larger view
The design is based on the USGloblSat EM-406A. The project costs less than $200 AUD and would have been much less if not for the extremely high shipping costs (USD $50) from the USA. The genuine GP-1 Nikon GPS unit costs $425 in Australia.
Both the GPS unit and remote shutter release use the same 10-pin connector. This means that I can only use one or the other. I then realised that I could add remote shutter release via a 2.5mm stereo jack connected to pin 9 (autofocus), pin 4 (shutter), pin 6 (gnd) on the Nikon 10-pin connector and using the remote controller from my Canon G10. It is a cheap one I picked up on Ebay.
The initial search to lock in satellites take a few minutes. The GPS logo on the Nikon flashes while it is searching and goes solid when it has locked in. The D700 has a battery saving mode and shuts down the GPS unit when not in use. However, I disable this initially otherwise it will keep turning off before it can lock onto any satellites. Once this has been achieved I then re-enable battery saving mode. The GPS module also has a built-in supercapacitor that backs up all the satellite location data making all subsequent GPS lock much faster.
The GPS data is embedded directly into the raw file with each press of the shutter. I then import all the photos directly into Adobe LR2 which supports embedded GPS data. In the library module scroll down to the bottom and you will see the GPS coordinates.
If you click on it, you need to be connected to the Internet, it will take you to the exact location in Google map.
I can also automatically export all my photographs directly from Adobe LR2 to PicasaWeb using Jeffery Friedl's "Export to Picasaweb" Plugin. I love this plugin! Its a donationware based usage model so if you use it and like it please send Jeffrey some money.
Check-out how I did it here and Check-out my project build pics. As part of my GPS testing I tracked my friend across Sydney. You can find out all the places he visited. Click on view map.