Re: Strange anomoly in WSJT-X waterfall display

[Josh Logan]

Have you verified the sample rate is 48,000 and not 44,100?

73, KD7HGL

Josh

On Mon, Nov 10, 2025 at 8:31 PM Larry Goodwin KC6WOG <lsgo...@gmail.com> wrote:

I  don't quite know what to make of this behavior. When I work FT8/4 with my HL2 setup, I usually (but not always!) see this strange distortion in the signal watefall, as though the frequency was drifting back and forth while receiving. Like the signal had a few too many drinks! It always settles down within several minutes and the signals start looking crisp and sharp, as they should. But it's not heat related, it doesn't matter if the HL2 has been on for ten seconds or ten hours and sometimes it doesn't happen at all, from a cold start! The audio sounds okay, although since the tones are already wavering in frequency, who's to say. It does decode just fine. Setup is HL2 connected to my laptop directly (not on my LAN) with audio carried over a virtual cable setup. I've tried both VB-Cable and  Virtual Audio Cable 4 (my preference) with no change.  Using VAC1 in Thetis v2.10.3.11.

The HL2 setup works brilliantly for SSB using cmASIO with my Steinberg USB preamp/interface, a few days somebody played my audio back for me and I was astonished at how "broadcast" it sounded.

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[Steve Haynal]

Hi,

I've seen strange distortion with FT8 signals when NR2 noise reduction is enabled.

73,

Steve

kf7o

[Liver Pudd]

Turn NR2 off then.

[Larry Goodwin KC6WOG]

Sample rate was correct and noise reduction was of course, not in use. But thanks for responses.

I asked on the Thetis Discord server and Reid immediately offered the solution. He suggested ticking the "Force" boxes in the associated VAC setup page with a value of 1. That immediately resolved the problem.