fldigi WWV calibration - unstable

kc2rgw
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Joined: Mon Jun 22, 2020 5:44 pm

fldigi WWV calibration - unstable

Postby kc2rgw » Mon Sep 14, 2020 5:58 pm

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.


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w9mdb
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Joined: Sun Apr 09, 2017 5:53 pm

Re: fldigi WWV calibration - unstable

Postby w9mdb » Mon Sep 14, 2020 7:21 pm

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
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w-u-2-o
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Re: fldigi WWV calibration - unstable

Postby w-u-2-o » Mon Sep 14, 2020 7:22 pm

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
Posts: 165
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Re: fldigi WWV calibration - unstable

Postby w9mdb » Mon Sep 14, 2020 7:42 pm

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?
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kc2rgw
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Re: fldigi WWV calibration - unstable

Postby kc2rgw » Mon Sep 14, 2020 7:49 pm

w-u-2-o wrote: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.
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w-u-2-o
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Re: fldigi WWV calibration - unstable

Postby w-u-2-o » Mon Sep 14, 2020 9:18 pm

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
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Re: fldigi WWV calibration - unstable

Postby kc2rgw » Tue Sep 15, 2020 2:13 am

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

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