AGPS - protocol specs?

Ian Stirling openmoko at
Thu Mar 8 14:19:40 CET 2007

Nils Faerber wrote:
> Ian Stirling schrieb:
>> 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.
> Darn.
> I do not care aout most of the chip, just the output format ;)

There probably isn't a clear line.

>> 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.
> You mean some kind of reverse engeneering trying to match the NMEA
> output to the raw input?

The gpsd will output assorted parameters, including current position, ...
You can take this - or even output from a nearby (1m) GPS, and the 
bitstream input and output to the GPS chip, and try to work out what the 
chip sends out.

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