locating via GSM, revisited

Andy Green andy at openmoko.com
Sun Apr 20 20:58:37 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:

|>>  To use this approach with GTA02 or GTA04/Diversity, it has to be
| evaluated
|>>  whether we can get he NCEL-list from our GSM-modems.
|> Yes, we can, the info at
|> came from my GTA01 modem but it works also on the GTA02 modem.  In
|> we also get the Timing Advance value (called tav).  We need some stats
|> :)
| Fine! Pleased to hear this :-)

WAH now you're talking :-)  I was very interested when you talked about
this before and hearing that this actually exists for GTAxx GSM is super

|> I'm not sure about forcing a reselection of the station but my guess
|> would be that there is a command for that also.
| If there's no such command already for it, we might probably be able
to hack
| it to the baseband firmware (OM may do this I guess).
| Andy Green mentioned he thinks he might have seen such a command
already. I
| will have some long nights to study the specs for GTA02 GSM modem, so
I can
| tell for sure. Wouldn't mind to get a pointer instead.. ;-)

(This is a misunderstand, I don't know anything about GSM commands.
What I was saying here inbetween beers was that I know Sean Chiang is in
control of the firmware enough to add his own commands, therefore I am
pretty certain we can add it if it doesn't exist.)

What I think we need to do with this stuff is feed it into one daemon,
from GPS, WLAN AP and GSM masts alike.  These WLAN and GSM
"fingerprints" have something deep in common, they are a list of
transmitters with estimated distance (radius) and estimated error.  I
think if we collect this datatype we can leverage it in very cool ways,
with or without the advantage of GPS.

Although pure signal strength or reflections can make variations in what
we think about one transmitter, it is unlikely to affect the
constellation of transmitters randomly spread around in the same way,
this stuff could be more robust than one might expect.

- -Andy
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