AGPS - protocol specs?

Ian Stirling openmoko at
Thu Mar 8 13:37:14 CET 2007

Nils Faerber wrote:
> Hi!
> I am interested in doing a little research on the AGPS part. As far as I
> understood the used Hammerhead chip will dump out the more or less raw
> GPS data into userland which will then need to be post-processed in
> order to get the usual NMEA or whatever messages.

> So, can OpenMoko provide at least somemore information about that chip
> and especially its output?

No, the chip is under NDA. has the current state of play.
Basically, the satellite format is known, and not especially hard to 
decode especially if we also get NMEA (or whatever) output out of the 
supplied daemon at the same time to decode it.

There is all sorts of wacky stuff - for example, peer-peer DGPS that can 
be done, where all stationary neos on charge with a GPS signal and a 
free internet connection contribute to a global ionospheric model.
Then any Neo can connect to this model, download 200 bytes or so, and 
get +-0.3m (or better) position for a short while.

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