GPS

Francesco Cat heartcollector87 at gmail.com
Mon Jun 23 19:31:04 CEST 2008


Ok I really missed what I wanted to say: One of my friends told me
some phones have positioning sistems that are quite unaccurate: they
should be based on cells but have no GPS. He also told me it was "AGPS
that uses only GSM to get information about position". Next time I
will document better instead of just listen to friends :P
Sorry for the big mistake

2008/6/23 Marcus Bauer <marcus.bauer at gmail.com>:
> On Mon, 2008-06-23 at 10:25 +0200, Federico Lorenzi wrote:
>> This seems to be really misunderstood. The GPS is the Freerunner can
>> get a fix with no help whatsoever, it'll just take longer. This is
>> where the AGPS can come in. Download some data off an assistance
>> server, and suddenly your time to fix is much less. There have been
>> posts to this mailing list about it.
>
> My experience with the Freerunner is ~12 minutes TTFF (time to first
> fix) without use of agps and ~4-8 minutes TTFF with agps from
> agps.u-blox.com using the software from openmoko.
>
> The Neo1973 (GTA01) had a TTFF without agps assistance of ~2 min.
>
> However, the freerunner shows correct altitude above geoid whereas the
> Neo1973 shows only height above WGS-84 ellipsoid. Depending on your
> location the difference between WGS-84 and geoid introduces an error
> from -102m to +86m towards your real altitude.
>
>
>
>
>
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