Problem using CFC audio tools in VAC

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rbduck
Posts: 327
Joined: Tue Dec 03, 2019 1:49 pm

Problem using CFC audio tools in VAC

Postby rbduck » Fri Sep 23, 2022 8:09 pm

This probably has a simple answer that I am overlooking. It has been a long time and I want to use the CFC to go through my audio chain and tweak settings. I haven't changed microphones so there should be little change. My problem stems from the fact I cannot get an audio display
with the Panadapter unless I add Drive. There is no audio representation with zero Drive. I know I had no issues with this the first time I did it a couple of years ago with one slight difference. The first time I did it I was feeding the audio from the microphone through the Mic input on front of the transceiver. Now it's done with the microphone input on the PC and completely through VAC.

I really would prefer not to have Drive (rf output) the entire time I'm doing the audio tuning it. What am I missing?
73
Ruben
NB4R
Apache-Labs Anan 7000DLE MKII Black -- Thetis 2.10.3.6 dev_2 -- Windows 11
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w-u-2-o
Posts: 5539
Joined: Fri Mar 10, 2017 1:47 pm

Re: Problem using CFC audio tools in VAC

Postby w-u-2-o » Fri Sep 23, 2022 8:42 pm

Can't understand why this got posted in the PureSignal sub-forum. Moved to the Thetis sub-forum...

The problem is that the panadapter is not an audio display, but an RF display.

However...

When in DUP mode the spectral display shows what is on the RX1 input during TX. With no RF drive you see nothing.

With DUP turned off the spectral display shows a representation of the digital input to the digital-to-analog converter (DAC). This will allow you to see the digital representation of your output signal prior to conversion to analog and RF amplification. This is also the point at which MON picks off it's signal. Since the drive control affects the DAC reference voltage and, on newer ANANs a post DAC attenuator, having DUP turned off still works with zero drive.

Also important: in either case, DUP on or off, if you are using MON to listen then PureSignal should be OFF, because PureSignal predistortion is applied prior to the DAC input and it will make the MON audio predistorted.

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