Playing around with GPS

Mike Montour mail at
Thu Aug 30 06:46:05 CEST 2007

One of the Neo1973's big selling points is its Hammerhead AGPS chip, 
however (with the exception of a few P0 developers) we haven't been able 
to do anything with it yet due to the lack of a driver.

I have recently joined the "Sphyrna" reverse-engineering project at (linked from, and with the 
assistance of the information provided there I have put together a quick 
and (very) dirty program called "satscan".

This program scans for signals from GPS satellites at several different 
Doppler-shifted frequencies, as a real GPS receiver would do during a 
"cold start" acquisition. It displays symbols on the screen representing 
the strength of each detected signal.

That's _all_ that it does - this program does not receive any navigation 
data from the satellites, does not compute a position fix, or anything 
else. It is strictly a 'toy' application, but at least it lets you 
confirm that your Neo1973 actually has a GPS chip installed. :)

It's available for download at: and it 
was built against a fairly recent 2007.2 image. You might need to 
"--force-depends" the installation. A source tarball is in the same 
directory, but I can't provide assistance on how to set up your 
development environment to build it.

I don't plan to maintain this program - it's a one-off demo. However I 
will continue to contribute to the reverse-engineering efforts, and I 
encourage any other interested developers to do the same.

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