On Fri, Jun 6, 2014 at 7:00 AM, Jerry Feldman <g...@blu.org> wrote: > Actually triangulation is used in GPS also. It is a very old tried and > true method.
Very true. Some difference are: 1. GPS is triangulation from satellites rather then cell towers 2. GPS was designed explicitly to provide location information and is available anywhere the sky is sufficiently visible. 3. GPS triangulation is done in the endpoint while the cell tower one is done cooperatively by the cell network as a whole. 4. GPS can be done passively by anyone anywhere, while cell tower triangulation requires endpoints that transmit (and as a result identify themselves.) I think that #4 is particularly interesting. I had a recent discussion with my father-in-law about Google's driverless cars and he was concerned that this meant that people would be trackable via their vehicle. He didn't seem to realize that it was perfectly possible to do driverless cars with GPS and offline maps in a way that was untrackable. Of course, I pointed out that we all now carry personal tracking devices (cellphones) anyway so there is no need to track our cars. Bill Bogstad Note to #4: I could conceive of a system that worked via network triangulation where the endpoint broadcast a random token which was used by the cell towers to triangulate the anonymous endpoint. I'm pretty sure that isn't the way it is done and even if it was the network would still know SOME device was at a particular location. It's interesting to note that because GPS was intended for dual civilian/military use, it was a design requirement that silent endpoints could determine their location. Privacy (of location) was obviously mandatory for military users. _______________________________________________ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss