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Measuring time of arrival of sound pulse

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Pald, Aug 16, 2017.

  1. Pald

    Pald New Member

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    How can one measure arrival time of sound pulse( in micro or nano seconds) at different mirophones( say five) using tablet or pc or any other equipment?
     
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi Pald,
    Which type of sound noise are you wishing to measure and over what distances.?
    E
     
  3. tomizett

    tomizett Active Member

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    The signal integrity of sound through air is not very good: there is noise, reflection, frequency-dependent attenuation etc. For this reason, it's generally not practical to directly measure the arrival time of edges as you might in the electrical domain (in time-domain reflectometry, for example).
    Instead, what is normally done is to inspect the cross-correlation of the transmitted and received sound. You will see a spike in the cross-correlation function at the point where the offset between the two waveforms equals the time-of-flight between the transmitter and receiver.
    See: https://en.wikipedia.org/wiki/Cross-correlation

    Of course, this relies on you knowing what sound was transmitted. Will you be in control of the sound that is produced, or is it going to come from an external source?
    It also works better with a stimulus sound which is periodic over a period significantly longer than the expected time-of-flight. A maximum length sequence is often used for this, although music can also be good.
    See https://en.wikipedia.org/wiki/Maximum_length_sequence

    Hope this provides some ideas.
     
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  4. dave

    Dave New Member

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  5. flatfootskier

    flatfootskier Member

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    is this, buy any chance, a gunfire locator query?
     

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