I saw a presentation about "opportunistic radio SLAM" which uses naturally occurring radio signals: TV transmitters, mobile phone masts and even analogue music

I saw a presentation about "opportunistic radio SLAM" which uses naturally occurring radio signals: TV transmitters, mobile phone masts and even analogue music radio to passively provide relative location data. The demonstration was amazing, some cleaver processing and you can figure out pretty much where you are (even inside a building). If ships had DPSLAM then they would have better location data: http://www.cl.cam.ac.uk/~rmf25/papers/Opportunistic%20radio%20SLAM%20for%20Indoor%20Navigation%20using%20Smartphone%20Sensors.pdf http://www.cl.cam.ac.uk/~rmf25/papers/Opportunistic%20radio%...