[Elecraft] [K3] AGC White Paper

[Ed Muns]

Decoders operate on the audio stream presented to them from the receiver.
The decoding algorithms use the difference in audio level at each instant in
time to make bit decisions.  AGC reduces those differences and thus
increases the bit error rate.

Of course, it is important to adjust the absolute audio levels so that the
dynamic range of the signal(s) is placed within the dynamic range of the
decoder.  But, compressing the dynamic range, i.e., AGC, increases the error
rate of the decoder.

Ed W0YK
_________________________________________________________________

-----Original Message-----
From: Bill Frantz [mailto:frantz at pwpconsult.com] 
Sent: 07 March, 2017 13:05
To: ed at w0yk.com
Cc: elecraft at mailman.qth.net
Subject: RE: [Elecraft] [K3] AGC White Paper

What I get using a relatively flat AGC is automation of my 
riding the RF gain control. I don't see how this kind of 
automation affects decoder performance. It should help 
performance as the decoder has a nearly constant level signal to 
work with. Please explain.

Thanks - Bill AE6JV

On 3/7/17 at 11:37 AM, ed at w0yk.com (Ed Muns) wrote:

>Just the opposite.  Most digital signal decoders work best with the least
>AGC action possible, even AGC Off.  AGC constrains decoder performance.
>
>Ed W0YK
>_____________________________________________________________________
>
>-----Original Message-----
>From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bill
>Frantz
>...
>Now to use SLP=15 for digital, where I want the AtoD to not 
>have to deal with a big range, while using something with more 
>dynamic range for voice/CW.

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