Proper USB signal modulation

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Proper USB signal modulation
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One item that has me perplexed is setting up the proper audio level using the SignaLink interface. From what I have been experiencing, WSPR might be a bit finicky about how much or how little audio is in the signal. In my case, I have been concerned that stations in the net are not decoding my signal for this reason.

Now that my SM-220 is back on line, I am a bit more confident in where to set the audio level. Of course, this is tricky because there are so many places where audio can be raised or lowered (i.e., the TX knob on the SignaLink, the Windows control panel, etc.)

At any rate, I have it to where I think it's optimal, but want some expert opinions. I am attaching a photo the scope and I would invite comments. Is this where it should be?

At this setting, the TX knob on the Signal link is rotated a small fraction from zero. Literature on the Internet suggests that this waveform would represent 100% modulation for a two tone signal. It's great to have the tools, but without knowledge of the theory, I might was well throw rocks.

Thanks for any feedback.

Bob Tarwacki, NY2M