PPRuNe Forums - View Single Post - Malaysian Airlines MH370 contact lost
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Old 9th Apr 2014, 13:55
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Self Loading Freight
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The latest TV news briefing said that the frequency received was 33.331 kHz, which is very precise.

Back of the envelope calculations assuming speed of sound in sea water at 4 degrees C and 4000 metres is around 1500 m/s, and the ship is towing at around 1 m/s, gives me a maximum doppler shift to the signal of around 20 Hz, which is an order of magnitude greater than the resolution indicated by the news report.

This is best case and assumes movement directly towards or away from the source, that there aren't effects due to currents, and that I haven't got my maths and assumptions wrong. Also, with 10 ms pings and the small windows of acquisition, there aren't that many waves to measure. Further, the signal seemed quite broad on the waterfall on the news report, but I couldn't make out bandwidth.

But - is it possible or even plausible that some further geometric information about the pinger's location wrt the receiver could be obtained this way? Perhaps the thread readers with DSP/hydroacoustic experience could comment...
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