Voice activity detector circuit?

Discussion in 'The Projects Forum' started by MikeML, Sep 20, 2015.

  1. MikeML

    Thread Starter AAC Fanatic!

    Oct 2, 2009
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    I'm looking for a simple voice activity detector circuit (VAD) I can put between the audio output of a VHF receiver and an Arduino. I already have a positive logic signal from the receiver to the Arduino that says that the receiver is receiving a carrier (Carrier Operated Squech=COS) detector.

    I would like to have a second detector whose output says that there is a strong likelyhood that the carrier that the receiver is detecting is modulated with human voice. I dont need to recognize what is being said; just that the receiver is detecting a voice-modulated transmission.
     
  2. bertus

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    Apr 5, 2008
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    Hello,

    The type of detector would depend on the modulation type.
    With FM the carrier is always present and you will need to detect variations in the frequency.
    With AM you can detect amplitude changes.

    Bertus
     
  3. MikeML

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    The receiver happens to be an AM receiver, but the circuit I am seeking connects between the audio output of the receiver and the Arduino input. The modulation method shouldn't matter...
     
  4. bertus

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  5. MikeML

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    Thanks Bertus,
    That one is just a AC rectifier; not frequency specific, no detection of voice cadence or envelope.
    Ditto.

    I would prefer something that checks for voice frequency components, and looks at the temporal aspect of the speech envelope...
    I think the former I could do in hardware, and the latter in the Arduino software?
     
  6. ScottWang

    Moderator

    Aug 23, 2012
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    I'm not sure is this match what you want, please check The sound active control circuit.
    The original that I was deigned to use the Applause to active the relay, so you may try to adjust C4, R6 to match your need or set a voice trap to catch the range of frequency.

    [​IMG]
     
  7. AnalogKid

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    Aug 1, 2013
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    be80be likes this.
  8. MikeML

    Thread Starter AAC Fanatic!

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    Good info.

    4600 posts on AAC; 9300 posts on ETO. I read both daily.
     
    be80be likes this.
  9. bertus

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    Apr 5, 2008
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    Hello,

    In the old days, the voice region was set at 300 - 3000 Hz by the phone companies.
    Make a filter that filters that range for voice info.

    Bertus
     
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