jisakiel at yahoo.es
Tue Jun 24 20:33:19 CEST 2008
As a matter of fact that database would not even be needed, as we *do* have a GPS to get positions. So, for instance:
- A location is defined somehow, and *beforehand*. Say manually while being there, perhaps with some precission range attached (high: 1m, low: whatever error margin the GSM have). Or perhaps entering latitude and longitude, gotten from google maps manually or whatever.
- That location consists in some GPS coordinates, perhaps some wifis visible, and basically in which towers are we connected to.
- When in range again of those 3 GSM towers, we know we are "close" to the location defined, and depending on the needed precision we can turn on the GPS if needed. Perhaps even the distance can be calculated more or less easily from the GSM signal information (I'd have to have a detailed look at
http://wiki.openmoko.org/wiki/GTA01_gsm_modem#AT.25EM and its applicability to GTA02 , but a quick glance shows some promising information:
" This information together with the list of neighbouring cells could be used for geolocation and potentially yield better results than using Signal-quality values for that.
- A different can of worms would be associating coordinates to an address, but we wouldn't need that from the beginning. For it, we'd need map info, or a quick connection to the net and glancing in google maps, for example... but to realize you've entered home you don't need that, just defining what "home" means should be enough.
Of course all of this would have to take into account possible changes in the towers (new ones added / tower ID changed / whatever) or the environment (changed AP names), but it doesn't seem impossible :).
If those AT commands are still present in the GTA02 recognising a former position would definitely be possible without too much battery usage (i hope ;) .
--- El mar, 24/6/08, john <jptmoore at gmail.com> escribió:
De: john <jptmoore at gmail.com>
Para: "List for Openmoko community discussion" <community at lists.openmoko.org>
Fecha: martes, 24 junio, 2008 2:45
Well if you mean obtain coordinates via triangulation it is
technically possible but in reality we are constrained by the GSM
operators and what information they are willing to give us. If you are
a large corporation such as Google and throw them some money you will
get access to such data. As Joe Public you will probably have to rely
on closed third party API's (e.g. Skyhook) to access similar
functionality or alternatively try one of the community driven
database lookup approaches.
2008/6/24 Jisakiel <jisakiel at yahoo.es>:
> - Is it possible then to fetch approximate position from the associated
> towers then? I guess it depends on the subset of commands the chip
> implements, but I didn't have the time to read over those
> documents as I'm still finishing my exams. I somehow suspect though
> GSM commands do not cover for that, and that'd be proprietary for the
> chip... Please correct me if I'm mistaken. I have no idea as well on
> precise is that.
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