Flex Integration AGC Effect - Fast vs Slow AGC

[K9YK Radio]

Here are a couple of quick videos that show the difference between Fast and Slow AGC settings when using FreeDV when using the Flex Radio waveform integration.  Slow AGC has a definite advantage.  Fast AGC produces more robo-tronic sounds between words and when the person transmitting is inhaling.    I think in general, people are using too much mic gain.  To sound good you need to use low mic gain and get very close to the mic.   The idea is for the mic to only capture the sound of your voice and nothing else.  I'm guessing that the codec is looking for vocal phoneme sounds and it doesn't know how to handle other types of noises like the sound of inhaling or fans running in the background.  

https://www.youtube.com/watch?v=0R9oDsyfWsY

https://www.youtube.com/watch?v=uLcE0GCIzjo

Mark (K9YK)

[Andrew O'Brien]

Very useful, thanks Mark

Andy K3UK

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Andy

[Stefan N.]

Can confirm that and realized that by chance.

Setting the AGC-T to „0“ helps too.

In the direct comparison, the waveform audio sounds not so smooth as usual, even with a low mic gain.

There is a 3-4 sec. delay on the decoding (which was present too in earlier versions of the codec) at the beginning of a transmission before it decodes well.

That’s my experience so far. 

Stefan - DF6VI - RasPi4+

[Michael Walker]

What are your RX Bandwidth settings?   You should be able to about 750hz to 2250hz based on what is being transmitted.  

Mike va3mw

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