fldigi WWV calibration - unstable

[kc2rgw]

I've been stumped for several days on this one.

Running fldigi, using VAC for the audio, all was perfect, WWV calibration was dead straight. Same firmware, same software, ran for a few weeks, consistent and solid.

I fired up the other day and saw the signals on the waterfall wobbling all over, so I ran the WWV cal in fldigi again and it looks like a squiggly s-curve down the display.

I'm familiar with it being on an angle either way and shifting ppm to calibrate, but I've never seen it as a squiggly varying line before on any rig.

I am totally stumped by this as I've changed nothing and suspect a Windows 10 patch possibly as the culprit.

Have any of you seen this instability as of the last few weeks?

Firmware 2.0.0b Thetis 2.7.0 a3
Focusrite 8i6 Scarlett
Win10 Pro current patch rev

All of the above have been a constant aside from any Win 10 patches

I've even recently done a db restore, no change.

wwv-cal-wtf.png (31.77 KiB) Viewed 10920 times

[w9mdb]

I'm running Windows 10 Home Version 1909 build 18363.1082 and just did a WWV test on 10Mhz and it's rock solid.

Sounds like little like your TXCO is unstable. Did you do this shortly after you transmitted? Heat can affect things.

Mike W9MDB

[w-u-2-o]

Please post a screen shot of your Thetis VAC setup window. It may be that the resampler is running in an unstable fashion for you. Do you see increasing under or overrun counters when this is occurring?

[w9mdb]

I get the same behavior if I don't force the VAC1 Monitor "TO VAC:"
I'm using Eltima VBCable. Is there some other setting to change?

Capture.PNG (231.68 KiB) Viewed 10910 times

[kc2rgw]

Please post a screen shot of your Thetis VAC setup window. It may be that the resampler is running in an unstable fashion for you. Do you see increasing under or overrun counters when this is occurring?

No, I'm familiar with that. I tried shifting sample rate and buffers around even.

I have the issue whether buffer is in manual or unchecked and the VAC1 Monitor To and From are both unchecked for the force boxes.

The setup tab shot is with me operating SSB at this moment, the only change to it is instead of the ASIO, it would have MME or Direct Sound with a virtual audio cable selected.

No underrun or overflow issues.

[w-u-2-o]

If it's not the resampler issue then it's either got to be a bad TCXO, or the hardware is somehow selecting a non-existent external reference, or something with the PC, although I'm not certain what the latter issue would be.

Do you have another PC you can try?

[kc2rgw]

That’s a thought, will doublecheck the time source on the sound card tomorrow to be sure it’s all still on local.

[kc2rgw]

This was all due to Malware Bytes being installed, I had Thetis whitelisted too but it did something to manipulate the packet flow. This software caused a bunch of other issues as well, losing control of the hardware as an example. I removed it and now everything is running very very well again.

Everything runs best with sample rates all at 48000 as well, it works with others but things are best on my end with the Focusrite 8i6 when everything is fixed, including the virtual audio cables at 48000.

[Tony EI7BMB]

Good info thanks

[kc2rgw]

I had this instability problem poke its head up again and I think I finally have it nailed.

I toggled the buffer latency to manual and dialed them in and I also toggled both Force options in VAC1 Monitor section, checking the Force box.

It's dead stable.

I think due to vagaries of other apps running on the PC that having the resampler enabled fouls it up.

This drove me crazy for a long time, hope it helps someone else.

[w9mdb]

And turn off the Web protection in Malwarebytes.
I've been working with them on the interference the web protection is causing with Thetis...in my case the transmit audio stops.
Mike W9MDB

[kc2rgw]

Yeah I just outright removed Malwarebytes and my Anan is running the best it ever has.

[K1LSB]

I use Bitdefender Antivirus free edition, it's very low overhead and doesn't seem to interfere with Thetis or any other use of the PC (I have Thetis added to Bitdefender's exclude list).

[w9mdb]

Malwarebytes fixed the interference with Thetis.
I'm now running with the Web protection turned on without any problems.
It's version 4.3.0

Mike W9MDB