Voice activity detector circuit?

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
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.
 

bertus

Joined Apr 5, 2008
22,270
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
 

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
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
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...
 

Thread Starter

MikeML

Joined Oct 2, 2009
5,444
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?
 

bertus

Joined Apr 5, 2008
22,270
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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