Joerg Reisenweber wrote:
Am Sa 4. April 2009 schrieb Stefan Schmidt:
OpenBmap likes to have more fields
for quality informations about GPS and GSM.
I strongly suggest to include fields for TimeAdvance values for each BTS.
TA is a much better and more reliable value for distance to Base Transmitter
Sation than dB signal strength.
See:
http://lists.openmoko.org/pipermail/openmoko-kernel/2008-April/002434.html
and
http://lists.openmoko.org/pipermail/openmoko-kernel/2008-June/002987.html
I see no problem with storing the TA, to allow testing of algorithm
using this (and thanks for bringing that to my knowledge).
Some precisions about openBmap approach. We do not try to locate or use
location of the BTS by itself. We try to build a coverage map of every
cell. What is the area where we have been connected to the cell. Then we
try to find a position for this area which makes sense (e.g. barycentre).
We do not so far use the signal strength for this. We thought about
using it nevertheless for positioning afterwards: get "position" of the
serving cell, plus neighbours which have signal strength strong enough
to make sense, and try to correlate all of this to refine the final
position.
Onen
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