[FSO] Speed gps time to firxt fix up?

Daniel Willmann daniel at openmoko.org
Thu Jan 29 22:28:30 CET 2009

On Fri, 16 Jan 2009 06:23:29 +0100
"Marco Trevisan (Treviño)" <mail at 3v1n0.net> wrote:

> Daniel Willmann wrote:
> > It actually does have memory, but lacks a backup battery which is
> > supposed to power the memory of the GPS while main power is off.
> > ogpsd already stores and restores almanac, GPS/UTC timeoffset and
> > approximate last position. It's not restoring ephemeris because I
> > had weird problems with that (TTFF increased to several minutes).
> Thanks for the information. How much do you think we could decrease
> the TTFF off, by restoring the ephemeris (in the right way, I guess)?

The manual claims down to 5 seconds TTFF if you supply ephemeris and a
precise timepulse.
Without the timepulse TTFF is supposed to be around 24 seconds.

> I've not tried recent versions of the Framework with the GPS, how long
> does it take generally to get the fix, nowadays?

At optimum conditions it takes about 30 seconds. The problem is that it
will take much longer if you are moving or generally don't have optimum
conditions as then downloading ephemeris will be interrupted frequently.
My hope was that TTFF will be much less susceptible to non-optimum

Daniel Willmann
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