I concur about AGC. It is supposed to be automatic and not manual. I use
medium or slow AGC for CW and SSB reception. I ALWAYS run my agc threshold
at 0.37 uv and RF gain full. I cannot find any example of an improved
signal to noise ratio by either reducing RF gain or increasing AGC
threshold. I just let the AGC control these things and I find it does a
fine job. Now if I were using fast AGC, then the noise would go up in
between CW elements and in between words on SSB. But slow or medium AGC
removes this from happening.
Carl Moreschi N4PY
Franklinton, NC
----- Original Message -----
From: "Marijan Miletic, S56A" <s56a@bit.si>
To: <tentec@contesting.com>
Sent: Tuesday, March 02, 2004 8:55 PM
Subject: Re: [TenTec] guide to adjusting Orion receiver;filters and
performance
> YT1NT> Internal (AGC) mechanism is immaterial.
>
> Analog AGC (it should actually be AGR_eduction) has a fixed parameters and
> its main function is to prevent DSP A/D input overflow.
> As long as this is under control, digital AGC can do all the math wonders
of
> system theory with CPU memory help.
>
> YT1NT> DSP noise reduction acts similar to your description, but it is
based
> on
> selective and adaptive filtering, not on simple gain change. And it works
> only with signals strong enough to be distinguished from noise in short
> time.
>
> DSP noise functions are based on long time recursive routines dealing
mainly
> with repetitive cyclic signals versus random amplitude/frequency noise.
>
> YT1NT> All the fuss is about preventing AGC to interfere with weak signal
> reception.
>
> This is done on statistical basis while hams prefer unique propagation
> cases!
> AGC is supossed to be A_utomatic and NOT manually controlled...
>
> 73 de Mario, S56A, N1YU
>
>
>
>
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