Reason for GPS problems found!

JW jameswillmer at googlemail.com
Fri Jul 18 15:49:59 CEST 2008


>
> 2. Tested GPS TTFF without SD card (from an indoor position not near a
> window): 306s
>
> 3. Shutdown and insert SD card
>
> 4. Tested GPS TTFF with SD card (from same indoor position not near a
> window): 484s



Nice test but I have a concern that only simulataneous test is a fair one
(two FR side by side)
This is because gps satellites are constantly moving (2 orbits per day) so
results can change

http://en.wikipedia.org/wiki/Image:ConstellationGPS.gif

Therefore I don't think we can place too much weight on time difference
above in case particular building configuration in your in-door test
suddenly shaded one crucial satellite....

Overall, getting indoor gps fix at all is pretty impressive - SIRF III is
great chipset.
If you bought GPS from 5 years ago this would be impossible for phone app.
Also my (last year) O2 XDA Orbit is will not get indoor gps lock....

JW
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