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IF GAIN

Posted: Mon Jun 05, 2017 5:34 pm
by IZ2245SWL
On 10m in USB, the AGC started to work on the modulation of a strong station near my frequency. The RX AGC was set on SLOW as has to be for SSB, I guess. After some attempts I solved the issue disabling the IF AGC on the main settings panel. The question is: what disadvantages have I disabling it? :?.

Re: IF GAIN

Posted: Wed Jun 07, 2017 6:20 pm
by W2DLC
One disadvantage is that your gain will not vary to match the signal on your precise listening frequency. You could solve this problem by using a notch filter and notching out the nearby offender.

Re: IF GAIN

Posted: Thu Jun 08, 2017 5:07 pm
by IZ2245SWL
I tried to use the Notch too, but the QRM station was too far in frequency.
A remark: I downloaded the SDRconsole V2. Its default, for the IF gain, is -20 dB manual even though the automatic option is available. :?:

Re: IF GAIN

Posted: Fri Jun 09, 2017 5:45 pm
by W2DLC
You can move the position and width of the notch in the EX control window of SDRUno. I set mine to go on either side of my receive bandwidth filters.

Re: IF GAIN

Posted: Sun Jun 11, 2017 12:38 pm
by hfsdpk11
A significant disadvantage in disabling IF AGC is exposing vulnerability to overdriving the ADC which leads to nasty things like images, intermodulation products and possibly de-sensing signals of interest. I think the overdrive warning flag doesn't work if you disable IF AGC, so you won't know the ADC input is too high until you see a degradation in the signals of interest.