I'm not saying there isn't an antenna issue, but that we may be able to mitigate the effects on startup time.
On Monday 07 July 2008, Kai Römer wrote: > Hi Al, > > Sounds really convincing, but how do you explain the constantly fast > fix via external antenna then. I really think its an antenna issue. > > Also the difference of the GPGSV values support this idea. > > Tomorrow evening i will ask a specialist to check the antenna signal > qualities. Maybe a cable is broken or there is a short circuit on the > main board. > > I ll report about the results. > > CU Kai > > 2008/7/6 Al Johnson <[EMAIL PROTECTED]>: > > From what I've seen on the wiki the version of the Antares4 on the GTA02 > > doesn't have the memory needed to store almanac and ephemeris, last known > > position or time. This means that every start is a true cold start, > > unlike every other reasonably modern GPS we're comparing it to. It starts > > up thinking the time is midnight on 30th November 1999 and seems to need > > a fair bit of decent signal to convince it otherwise, contributing to the > > long startup time. > > > > It looks like there is a way around this if you look at the documentation > > for the assist. The AID-INI message needn't be supplied by a remote > > server; we can generate it locally to provide the sort of data that's > > stored internally most of the time. At the very least we have a fair idea > > of the current time and date. We should also be able to store location, > > almanac and ephemeris when we shut down the GPS, and provide it at the > > next startup. We can also have a stab at current location, based perhaps > > on cell ID or wifi data as discussed by some of the other threads, or on > > user input. > > > > I'll try to patch together something to do this based on the example perl > > client and server code, and see how much difference it makes. > > > > On Friday 04 July 2008, Kai Römer wrote: > >> I can affirm this for 6 opemoko devices. i guess its an internal > >> antenna issue. as soon as you connect a external antenna to it works > >> like a charm. but fur me thats no solution. > >> > >> TTFF with external antenna (perfect condition): 40 to 60 seconds > >> TTFF with internal antenna AGPS (perfect condition): more than 1:20 > >> minute but not always. its like gambling. > >> > >> I guess a miss design of the internal antenna. > >> > >> CU Kai > >> > >> 2008/6/23 Peter Kraker <[EMAIL PROTECTED]>: > >> > This timings are insane unless you don't even have a valid almanac, > >> > which is rare. This doesn't look right. > >> > > >> > Yorick Matthys pravi: > >> > > >> > Marcus Bauer said: > >> > > >> > > >> > 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. > >> > > >> > > >> > 12 minutes without AGPS and 4-8min with AGPS?? > >> > I hope there was a thunderstorm inside the basement where you tested > >> > this... > >> > > >> > :) > >> > > >> > Seriously, these just don't seem realistic. > >> > Compare them for example with some other devices from 2003: > >> > http://www.pocketgpsworld.com/ttffcomparisons.php. > >> > Or from ublox: http://www.u-blox.com/technology/assistnow/ (table at > >> > the bottom of the page) > >> > > >> > Surely there must be something wrong with your > >> > software/settings/hardware/environment... > >> > (or maybe they still have a lot of work to do on the GPS :)) > >> > > >> > y _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
