[Elecraft] RX Mush, why the fuss?

Don Wilhelm donwilh at embarqmail.com
Tue Feb 28 20:34:41 EST 2017


I am not certain what it has to do with "mush", but it does seem to help.

What is certain is that if the AGC Threshold is set too low, the AGC 
will be activated on band noise.  Whether that 'band noise' is the 
result of ambient noise level, or the ambient 'noise' of a multitude of 
signals in close frequency proximity is for the user to determine.

As far as the slope is concerned, yes, the AGC will respond to the 
strongest signal in the passband, that is a fact.
The reason for setting the slope to something other than flat is not a 
consideration for reducing the RX Mush, but it allows the user to 
evaluate by ear the relative strength of signals.

In summary, signals below the threshold will be received the same as 
with the AGC off.  Signals above the threshold will be reduced according 
to the slope of the AGC response, but the strongest one in the passband 
will take control of the AGC.

It is nice to be able to report an S6 signal is weaker than an S8 or S9 
signal without depending on the S-meter.  Of course, all signals in a 
contest or for reports to a DX station are always 59 or 599.



On 2/28/2017 6:37 PM, dave wrote:
>
> My thoughts on this are that those who are concerned about the slope and
> threshold settings are barking up the wrong tree. The mush would result
> if you have your hold time or hang time or decay set too short. With a
> brief hold time the weaker signal pops up to the level of the stronger
> on as soon as the stronger one disappears. A longer hold time keeps the
> relative level of the two signals at the correct relationship. The
> answer is hold time, not threshold or slope.


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