I am working on a project where an array with multiple microphones will be deployed to calculate (via triangulation) the origin point of a burst of sound. As you can imagine, with sound traveling at 343 m/s under standard conditions, the temporal resolution of the sound data recorded by the microphones will have to be very high if I am to make a precise estimate of where the sound originated from. The finer the granulations of data, the better the estimate.

My question is, what is the minimum time increment you can record with a microphone (or other instrument) with a Raspberry Pi? Am I correct in thinking that it would be the same as the clock speed of the device itself (i.e., a 1.5GHz Pi would be able to capture data in 1.5GHz of resolution)?

  • wouldn't the sampling rate also be a factor (you say "recorded by microphone" - so I'm assuming - probably wrongly - that you are using some sort of ADC?) - also, what is the minimum rate that you think would be useful for your purpose Apr 8 at 2:56
  • If the resolution of the data was 600MHz, then for a target at 150 meters you could determine its location within about 2.5cm – that's the kind of resolution I need. Could you explain the sampling rate further?
    – Alex Heebs
    Apr 8 at 3:13
  • ADC's have a sample rate - I assume you're using some type of ADC's to sample the microphones .. ADC -> Analog to Digital Converter Apr 8 at 4:21

Consumer microphones are made for audible sound range and will therefore be useless above ~20kHz, no matter how fast you sample.

You should use specialized receivers, similar to those the famous HC-SR04 modules use. Those modules have a useful bandwidth of about 100kHz and a resolution of about 5 mm. Higher frequencies would give you proportionally better resolutions.

You will certainly not be able to sample at CPU clock frequency, no matter what device you pick. The Pi has no ADC to begin with, so the sampling rate will largely depend on the additional hardware you will buy.

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