Distorted tx-audio on TX-Profile change

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oe3ide
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Distorted tx-audio on TX-Profile change

Postby oe3ide » Fri Jun 04, 2021 7:29 am

Hi,

Sometimes it happens that the TX audio is distorted after changing the TX profile. From this point on, no TX profile "works" anymore, ie. in every TX profile the TX audio is distorted. The problem is unfortunately not reproducible, but occurs from time to time.
Solution/Workaround: Restart Thetis or changing the sample rate from 48,000 to 44,100 and back to 48.000.

My audio seems to be very stable at the moment. Worked this week continuously about 2h (about 70 QSOs with the states) .. no glitches, no distortions ...

My friend Peter, HB9UQX also has the same problem, but he "loses" his TX audio on TX Profile change. He is using OpenHPSDR mrx.

Any ideas?

73 de Ernst
OE3IDE
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w-u-2-o
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Re: Distorted tx-audio on TX-Profile change

Postby w-u-2-o » Fri Jun 04, 2021 10:31 am

Are you using VAC or is the mic plugged into the ANAN? If it's VAC please describe your VAC setup.
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Re: Distorted tx-audio on TX-Profile change

Postby oe3ide » Fri Jun 04, 2021 11:11 am

I am using VAC. Setup see screenshot.

I experimented already with Ringbuffers, but with no success.


Image 9.jpg
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Re: Distorted tx-audio on TX-Profile change

Postby w-u-2-o » Sat Jun 05, 2021 7:38 am

Sorry, I forgot you were using VAC. Of course you are, since there was a separate, lengthy thread on your setup.

Whenever you change any setting in the VAC control panel it will reset all VAC operations. This is why changing the sample rate works. However that is an ugly way of performing a reset. It is better to cycle any of the four manual checkboxes so that the rest of your audio system does not have to deal with changing sample rates.

So now the question is: why do you have to reset VAC after a TX profile change?

This begs another question: are all VAC settings identical in all TX profiles you are using? If not, then they need to be, and they need to be correct, too. This is because VAC settings are saved as part of each TX profile.

I did notice that in your earlier thread you said you were using a buffer of 256 with the Presonus. In this thread your screen shot shows 128. With luck this is the problem and the solution will be simple: just clean up the settings and resave each profile.
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Re: Distorted tx-audio on TX-Profile change

Postby oe3ide » Sat Jun 05, 2021 8:36 am

Hi Scott.. first of all, thank you for your patience and help!

re Buffersize: I have 128 in presonus, VMP and Thetis.. so all at the same buffersize.

I have now adjusted all VAC settings in all profiles. In the FT8 profile I had different settings for the ring buffer size.

Since the problem is sporadic, it is difficult to determine what exactly is causing it. I can switch profiles 10-20 times without a problem. But sometimes the problem just arises.
It is annoying that - without TX monitoring - you don't even notice that the tx-audio is distorted.

As soon as the problem recurs I will take a recording and post it here and trying to remember the previous steps.
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Re: Distorted tx-audio on TX-Profile change

Postby w-u-2-o » Sat Jun 05, 2021 9:19 am

oe3ide wrote:Since the problem is sporadic, it is difficult to determine what exactly is causing it. I can switch profiles 10-20 times without a problem. But sometimes the problem just arises.
That is important information. It seemed like you were describing a problem that happened every single time you switched profiles, not sporadically.

I also see this sporadic problem here. It is a problem with VAC initialization. Other than going to a much larger buffer size across the board it is likely that you will not be able to solve the problem, i.e. it is not anything you are doing wrong, or can fix, it is a bug in Thetis.

It is annoying that - without TX monitoring - you don't even notice that the tx-audio is distorted.
It never affects receive audio? I always notice the problem on both RX and TX.

As soon as the problem recurs I will take a recording and post it here and trying to remember the previous steps.
No need for this.
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Re: Distorted tx-audio on TX-Profile change

Postby oe3ide » Sat Jun 05, 2021 10:50 am

It never affects receive audio? I always notice the problem on both RX and TX.

Unfortunatly always only tx-audio...

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