Submission + - Finnish Hacker Isolates GPS Coordinates from Youtube Video Soundtrack (windytan.com)
An anonymous reader writes: "The signal sits alone on the left audio channel, so I can completely isolate it. Judging from the spectrogram, the modulation scheme seems to be BFSK, switching the carrier between 1200 and 2200 Hz. I demodulated it by filtering it with a lowpass and highpass sinc in SoX and comparing outputs. Now I had a bitstream at 1200 bps."