jm + power + crime   1

BBC News - The hum that helps to fight crime
'Dr Harrison said: "If we have we can extract [the hum of the mains AC power's 50Hz wave] and compare it with the database, if it is a continuous recording, it will all match up nicely. "If we've got some breaks in the recording, if it's been stopped and started, the profiles won't match or there will be a section missing. Or if it has come from two different recordings looking as if it is one, we'll have two different profiles within that one recording." In the UK, because one national grid supplies the country with electricity, the fluctuations in frequency are the same the country over. So it does not matter if the recording has been made in Aberdeen or Southampton, the comparison will work.'
buzz  hum  uk  mains  power  50hz  crime  forensics  bbc 
december 2012 by jm

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