Those Zoom FFT pages show -sin() as the multiplier for Q.

But a lot of other sources show +sin(), as I use in vlfrx-tools.

Andy's hardware is using +sin and the spectrum is correct in
Spectrum Lab but is reversed with vlfrx-tools/EbNaut.

And RTL2832 appears to use -sin() because I have to use -Q
in vlfrx-tools.

Wolf wrote:

> When loading Andy's file in a curve editor, I see the
> 2nd channel leads the 1st by 90 degrees.

That sounds like Q is using +sin() then. It's a puzzle why
Andy is having to give the opposite frequency offset to the
decoder.

Perhaps I'll sleep on this one.  I/Q signal processing is
always easier when wide awake.

--
Paul Nicholson
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