On Sat, 2009-07-04 at 19:56 +0100, Al Johnson wrote: > On Saturday 04 July 2009, Paul Fertser wrote: > > Sebastian Krzyszkowiak <[email protected]> writes: > > > On 7/4/09, Hammer Armin <[email protected]> wrote: > > >> With the internal gps antenna, the first fix last quite long - > > >> with the external - within 5min to 10min I get a fix. > > > > > > WTF? I'm getting fix easly with *internal* GPS antenna in 30 seconds - > > > 2 minutes... > > > > Because you already have almanac (and sometimes ephemeris) data. > > With a good sky view and suitable constellation TTFF from cold is ~40s with > the internal antenna, rootfs on SD and an early A05 without the capacitor on > SD. For it to take >2min I need heavy urban canyoning, being indoors or in a > vehicle, or an unusually poor constellation. > > Having almanac and ephemeris _should_ make it faster, as should > initialisation > with correct time and approximate location. Feed it incorrect data at startup > and you can get a very long TTFF, or no fix at all, and ogpsd has done this > at > some stages of its development.
and if you are carrying the FR in a pocket, yes it gets a lock most of the time, but the track wobbles all over the place - up to a hundred meters. And if driving through an "urban canyon", similar track errors can occur. Ive wanted a small external powered antenna for some time to improve this. BillK _______________________________________________ Openmoko community mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/community
