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SamQuan236 t1_isynqc2 wrote

Reply to comment by VolcanicBear in Can a submarine’s sonar pulses be detected and used to pinpoint location of origin? by Leumas404

if you encode the outgoing signal as white noise, it won't clearly correlate to reflections from the environment, as you would have to subtract the random additive noise from the emitter, which would drown out the quieter reflection.

however , if you know the sequence from the emitter in advance (say you know the random key) , then you can subtract it from your inbound signal, enhancing the signal to noise .

its a bit like radar jamming, or selective availability in gps.

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Coomb t1_it8w7cx wrote

This is grossly implausible for sonar for a variety of reasons, including (but almost certainly not limited to):

  • potentially very substantial added complexity to receiving microphones in order to extract spectral information from a sonar return (depending on spectrum used)
  • the extremely low bandwidth available from sonar pulses from emitters a practical distance away (at least tens to hundreds of kilometers if not more) because of the attenuation of higher frequency sound in water
  • the high frequency dependence of attenuation and dispersal of sound in water
  • the extremely challenging noise environment at usable frequencies
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