Warranty after fix for GTA02 GPS rework for SD card interference issue
andy at openmoko.com
Tue Jul 29 21:57:32 CEST 2008
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Somebody in the thread at some point said:
| The software fix alone allows you to get a fast TTFF but after that, sd
| card data transfers are just to noisy to maintain a high quality GPS
| data stream. Yes it works but poorly, which is better than not at all.
There's something to be aware of here, when getting the fix the GPS chip
needs a much better Signal to Noise ratio than when maintaining it.
Have a look at the first few lines of this:
– Acquisition Sensitivity: –142 dBm (Cold Start, With External LNA)
– Tracking Sensitivity: –158 dBm (With External LNA)
(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.
| I have two Fr's, once I get the caps(this week). I'll do the HW fix on
| one, install the software fix on both, and do a side by side comparison.
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.
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