[TenTec] Orion AVC

[Sinisa Hristov]

Bill Tippett wrote:

>  >AGC DECAY can be kept at 5 dB/s with AGC HANG time at 0.30 - 1.00 seconds.
> This minimizes AGC-induced interference with signals at noise level.
 
>          Very interesting Sinisa.  I have not played with such high settings
> of Hang and played with this on some very weak signals on Topband
> this morning.  Based on my limited use, it does seem to help.  Could you
> explain the theory behind this?  I suppose it simply slows down the AGC
> action to the point that it does not raise the noise level between CW
> characters.


AGC is inactive during "hang" time with gain held at fixed level
determined by the signal peak at the start of "hang" time.
Benefit is twofold:

  * constant gain eases the job of our neural system, in part by not
    raising noise level between characters/word, as you mentioned;

  * the usual AGC-induced intermodulation is avoided
    (AGC action essentially multiplies the signal with a rectified
     and filtered version of it, creating intermodulation
     which is particularly bad with a signal at the noise level).

I'm glad to see that my posts may be of some value.


73,

Sinisa  YT1NT, VA3TTN