Daniel Willmann wrote: > On Wed, 04 Mar 2009 13:59:07 +0100 > Helge Hafting <helge.haft...@hist.no> wrote: > >> Thanks a lot! >> I needed this one too, and now get 7s warm starts! >> http://git.freesmartphone.org/?p=framework.git;a=commitdiff;h=ad2ec48cdb5ab9bdddc15adfc05cbd2e5b8a2cee > > 7s TTFF is pretty good. I got that once, but usually I have about 16s > TTFF. > I do not get 7s every time. This was an ideal test, I was standing in a place with good visibility. the gps used 9 or so satellites. Then I stopped tangogps and restarted it, and timed it from the moment the tangogps screen showed. (So as to not include the startup time for tangogps itself). The TTFF is usually a little longer inside a bus or building.
>> I also raised pacc from 3km to 9km, as I often enough travel a bit >> more than 3km with the gps unit off. > > I'm interested to hear how that affects TTFF. The way I understand it > initial position is only used to calculate which SVs are in view so the > chip knows which SVs to search for. So a pacc of 3km or 9km shouldn't > have any noticable effect. This is just guesswork though, so any > results on your part would be greatly appreciated. It was just to be safe. The documentation states that you might not get a fix _at all_ if either position or time is outside the claimed accuracy. Now, maybe it works with 3km anyway after the fixes that prevents the chip-crashing exception. I happen to live about 6km away from where I work, so 9km was a nice safe value. The default is 300km, and "100km allows a more optimistic startup." Perhaps such rough estimates is all that is needed, if it is only used to figure which satellites that can be seen. Helge Hafting _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
