PPRuNe Forums - View Single Post - AF 447 Search to resume (part2)
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Old 12th May 2011, 13:48
  #1213 (permalink)  
JD-EE
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
GarageYears, if you know the cockpit noise has specific repetitive characteristics you can find them in the sample you're working with and subtract them out. The remainder would be the somewhat more random speech products. Pulling out the broadband random background is a different ballgame. It can make some difference. But it's not huge.

For example, in the really old days aircraft radios had dynamotors. They had a characteristic whine that could be filtered out. You can also filter out a lot of the low frequency sounds and still hear speech remarkably clearly. (Bose noise canceling headsets anybody?) So aircraft 400 Hz whine and things like that can be neatly removed along with the low frequency rush leaving very clear speech. I don't think that's going to help with already band filtered 36kHz to 39kHz audio.

In the pinger search most of the background noise is short bursts of coherent noise containing a series of short bursts of signal. Filtering out the whale song to leave the signal would be "interesting".
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