Warranty after fix for GTA02 GPS rework for SD card interferenceissue

steve steve at openmoko.com
Thu Jul 31 16:14:30 CEST 2008

Hmm. Jay...

  Amaybe when SD I/O occurs one could use the accelerometers to dead reckon?
They are noisy and drift
  but for short periods MIGHT be able to keep wild errors in mapping from

  Just a thought. 

-----Original Message-----
From: community-bounces at lists.openmoko.org
[mailto:community-bounces at lists.openmoko.org] On Behalf Of Jay Vaughan
Sent: Wednesday, July 30, 2008 1:24 AM
To: List for Openmoko community discussion
Subject: Re: Warranty after fix for GTA02 GPS rework for SD card

> (We have external LNA)  It means it can track with a 16dBm reduction 
> in GPS signal after it made the satellite acquisitions.  So if you 
> understood it will get a fix OK with the software workaround, and we 
> saw many people report this, you should expect the tracking phase to 
> work better than the acquisition phase since the signal requirement is 
> relaxed by 16dBm.

My experience has proven that this is not the case; yes the fix happens
sooner, but if SD I/O occurs during tracking phase, wild errors are still
introduced into the GPS signal sufficient to drive us off the map.

Just sayin', not trying to stir the pot.  I've been testing this GPS fix
every day since it arrived, by tracking my progress to work, and if I zoom
too closely (meaning there is more SD I/O on map refreshes) the GPS goes

> That'll be interesting.  But in the real world many thing perturb GPS 
> tracking and sophisticated software filters are anyway used to try to 
> see through excursions, I guess this will be the case for typical SD 
> Card usage pattern here.

My ride to and from work is through a wide open space with no obstructions,
lots of blue sky, and for sure .. SD I/O still massively impacts GPS
*accuracy*.  Not just in the acquisition phase, but also tracking ..

Jay Vaughan

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