Gergely Imreh wrote: > Hi > > > (...) > > Oh, yeah, sounds easy... The problem is that the cell does not > broadcast any location information, so the best you can do is the go > around town, record the signal strength, and try to guess where the > signal is coming from. If there's plain sight it is relatively > straightforward. We tried it in a city - echos, shielding from > buildings... imagine the rest, the signal was all over the place. Not > something that one can analyse without further knowledge or guesswork. > Can send you some logs if you want to check it out > Having a "cell fingerprint" database - storing relative strengths of > multiple cells together with the recorded GPS position - would provide > better operation, but with a cost (in storage place, for example) that > is just not worth the effort. With the current GSM methods one does > not aim for supreme accuracy, just speed (you can locate which > intersection in a city you are in a second, not within 10+ minutes it > usually takes with my GPS).
Hi, by simplifying a little but, this could become easier : assume that you log positions/cell relationships: for each cell ID, you compute the geometrical barycenter of the positions. You then store this position and its accuracy (the number of positions/cell relationships, maybe compute the geographical spread of the points) that you used to compute the mean. Assuming an dense, logging you would then have one position per cell, with a "quality factor" (~ how many measures have produced this point), you could then simply have a "nearest neighbour" approach to get to know where you are. It's true that you would not have the real antenna's positions, but you would have positions where many people have "seen" the cell ID, which could turn to be more accurate. > Cheers, > Greg Regards, OdyX -- Swisslinux.org − Le carrefour GNU/Linux en Suisse − http://www.swisslinux.org _______________________________________________ devel mailing list [email protected] https://lists.openmoko.org/mailman/listinfo/devel
