Help needed with GSM Geolocation without GPS

Al Johnson openmoko at
Tue Nov 6 20:35:25 CET 2012

On Tuesday 06 November 2012 08:09:58 robin wrote:
> > Sounds good.  I wonder what the trade-off is between implementing
> > something like this from scratch for GTA04, and trying to integrate an
> > existing partial solution such as GeoClue?
> hi neil,
> as far as I understand geoclue comprises a communication between a provider
> and your phone, so that would mean data transfer via the modem. This would
> certainly be one solution, but it would be nice if the user could choose
> between:
> a) GSM -> Provider -> Location
> b) GSM -> offline database -> Location (saves money and battery(?))
> I don't know if geoclue can be easily extended to use the cells.txt.gz file
> as an alternative input. That would be nice, because then one could actually
> choose between a) and b).

As far as geoclue's concerned a Provider is anything that implements the dbus 
interface. There's no reason for data to go over the modem, it's just that 
most of the current Provider implementations use online data services for 
lookup. You can install whichever Providers you want.

All(!) that's needed is a Provider that implements the Position interface, 
looking up current and/or neighbouring cells in the local file/database and 
returning a location extimate. IIRC that would be quite a simple dbus service 
to implement, at least as a proof-of-concept, but I've probably forgotten 
somehting important.

Applications can pick whether to use the Master Provider (which uses data from 
the 'best' available Provider) or a specific Provider, so you can have a 
choice between a) and b).

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