[Elecraft] [K3] AGC White Paper

[Wes Stewart]

  AGC adjusts the receiver gain, compared to the audio bits, rather slowly and 
DOES NOT change the "dynamic range."

If you're listening to a signal and it's too loud for your ears and you turn the 
audio gain down 10 dB, does that change the amplitude ratio of any signal you're 
listening to?  No, it lowers everything by 10 dB.  AGC is no different, it just 
operates at another location in the radio.

IMHO, this thinking is the result of looking at too many ACG slope, threshold, 
and phase of the moon charts and assuming that bigger signals have their gain 
reduced more that smaller ones at the same instant in time.

Wes  N7WS

On 3/7/2017 2:19 PM, Ed Muns wrote:
> 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
> _________________________________________________________________