[hpsdr] WSJT VAC, ALC and PowerSDR mRX PS

[Conrad Farlow]

That is spot on John and exactly what it was. I am up really late 
because I have been experimenting for the 1st time with remote operation 
and sure enough you were right.

Regards

Conrad  G0RUZ (definitely time for ZZZZ)

> I will admit to making this elementary mistake myself, so my apologies 
> if you have already looked at this. It seems you may somehow have 
> routed RX audio back to the TX. The easiest way to make this mistake 
> is to use only one virtual cable instead of two. The receive audio 
> continues to playback for a very brief moment after TX is triggered 
> due to the various DSP buffers and the VAC delay. Unlike a regular 
> sound card, VAC is continuously copying each virtual cable's input to 
> its output. Since VAC will mix multiple inputs to the same cable this 
> sort of thing can result. Make sure you have Cable #1 configured as 
> PowerSDR output and WSJT input and Cable #2 configured as PowerSDR 
> Input and WSJT Output.
>
> A very long time ago there was a different problem which caused the 
> same sort of behavior before the T/R transitions were reworked in 
> PowerSDR, but if you are on the latest releases of software and 
> firmware this should not be your problem.
>
> 73, John KF5SAB.
>
> On Sat, Oct 11, 2014 at 4:07 PM, Conrad Farlow <conrad at g0ruz.com 
> <mailto:conrad at g0ruz.com>> wrote:
>
>     ***** High Performance Software Defined Radio Discussion List *****
>
>     I am using an ANAN-10 with the latest version of PowerSDR mRx PS.
>     I have VAC working well with WSJT but I get a burst of noise just
>     before WSJT starts generating audio. It is 20dB below the
>     modulated audio and I suspect that is due to some kind of expander
>     action on the ALC. I am driving a transverter and have only 500mW
>     output to do so. My TX is very clean but is there any way of
>     getting rid of this, in fact turning the TX ALC off altogether? I
>     don't need it as the audio level is tightly controlled and I have
>     a the TX gain set at around 75dB. There is no way that I am going
>     to overdrive anything.
>     -- 
>
>     __________________________________________________
>
>     73
>
>     Conrad G0RUZ IO93FR
>
>
>     North Wakefield Radio Club
>
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