[Fun] Have you ever wondered of the GPS chip accuracy?

Al Johnson openmoko at mazikeen.demon.co.uk
Wed Aug 5 14:53:29 CEST 2009

On Tuesday 04 August 2009, Laszlo KREKACS wrote:
> I got two questions regarding the gps chip, maybe someone
> can answer me:
> - is there some settings, where I can fine-tune the gps
> chip? (I think what is the method to calculate the average speed?
> Is it adjustable?)

If you talk to the GPS directly using the UBX format you can change the mode 
to match your vehicle/usage type. This changes some of the assumptions it 
makes in location estimation. This isn't available through the FSO interface, 
but at least ome app (omgps?) is using it. Links to the UBX docs were in the 
wiki last time I looked. Remember you will have to disable ogpsd before you 
use it this way.

> - Is there a way to ask for gps coordinates faster then one second?
> (for running 0.1 sec would be awesome). And why the time is
> only reported in sec unit? (not fraction of the second)
> 1249424982.764385 vs. 1249424982
> Is it a limitation of the gps chip?

This came up on the list before. IIRC you can ask the GPS for more or less 
frequent reports, and the integer seconds are due to the FSO implementation 
rather than the GPS.

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