Interestingly, this is used to geolocate multimedia recordings, as different places will have different mains interference.
If you know roughly when a recording is taken and what the state of the power grid over the target area (country, region or state etc.) is, you can match the recording with its location - and vice versa.
If you know roughly when a recording is taken and what the state of the power grid over the target area (country, region or state etc.) is, you can match the recording with its location - and vice versa.
https://www.ece.umd.edu/~minwu/public_paper/Conf13/1305_ENFL...