[Lowfer] GBPSK data from last night

[Bill de Carle]

I have done a preliminary investigation of the audio data from last night's
NC monitoring on 186.05 Khz.  The results are instructive in one sense,
inconclusive in another.  Unfortunately I had too much audio level into the
DAC (was using 16-bit sound card) and it clipped a bit.  I had set up the
level with the rig's AGC "on" but I turned it off shortly after starting the
run and didn't notice it was clipping too much.  Oh well, c'est la vie.

Still, looking at the passband with FFTZZ:

	www.magma.ca/~ve2iq/sbdump02.gif

it becomes immediately clear that I had two humongous interfering lines in
the IF passband, one at 704 Hz and one at 849 Hz.  At least one of these
signals is the one that sounds like a "motor" I can hear easily.  The actual
800-Hz carrier from NC has to be at least 13 dB below these lines, and isn't
even discernable on the FFT.

I sliced out the first hour of the 8200 s/s audio file and converted it to
.WAV format.  Still kept the original samples but saved it as 5512 s/s to
make ARGO happy.  That means ARGO's time and frequency axes are compressed,
so we would expect our 800-Hz BPSK carrier to appear at 537.73 Hz on the
ARGO scale, and we'd expect the 2 interfering lines to show up at 473 Hz
and 570 Hz respectively.

I made 2 passes through ARGO, first using 60-seconds per dot, then using
3-seconds
per dot.  The screen dumps are here:

	www.magma.ca/~ve2iq/captnarr.jpg

	www.magma.ca/~ve2iq/captwide.jpg

Absolutely no sign of any BPSK signal at 537.73 Hz - but that could be in
large
measure due to the way Alberto does his processing.  I would not expect a
signal
with BPSK modulation at 1 bit per second to show up well on ARGO's 60
second or 3
second screens; still, thought there might be some trace of it.  The very
strong
QRM signal at 850 HZ shows up on the wide ARGO screen at 570 Hz (850 x 5512
/ 8200),
the other strong line is off-screen.

Looks like we cannot use ARGO to find BPSK signals - at least unless the
BPSK modulation
is slow enough to qualify as QRSS-BPSK.

Bill VE2IQ