thoughts on A-GPS offline

Daniel Willmann daniel at
Sun Mar 1 22:32:35 CET 2009

On Sun, 1 Mar 2009 21:39:25 +0100
Raphaël Jacquot <sxpert at> wrote:

> On Sun, Mar 01, 2009 at 08:31:16PM +0100, Daniel Willmann wrote:
> > Now that hot-/warmstart with ephemeris playback works with the
> > framework we should try to get an open server with aiding data
> > available ASAP.
> is there a way to get the ephemeris data from the gps receiver at
> some point ? it could be stored on the phone and used as a
> calculation aide...

Yes and that's what ogpsd does already. It has been saving/restoring
almanac for months, ephemeris was disabled up until recently because
there was a bug that prevented the GPS chip from doing anything useful
after they were restored to the chip.

The chip will use all available data to calculate the fix. With
restoring ephemeris this means a time to first fix of about 16 seconds
at the moment. Not sure how much faster we can get.

Daniel Willmann
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