WD2XES is running Opera32 on 137.520 kHz (136.000 USB) tonight.
W1VD and I have run a couple of daytime test sessions on Opera. It's
tough to make real science of this, given the vagaries of noise,
interference and fading, but we do have a few conclusions. In all cases,
our goal was to find the minimum power level needed to decode a message,
not just to follow the SNR figures provided by the various programs.
Opera2 is roughly equivalent to QRSS3. Haven't done any slower QRSS
tests yet. If there's some linearity, Opera32 might be as good as
QRSS30, but the issue of "all or none" copy brought up by M0BMU might be
important. The brain is a really neat processor.
Opera4 is about the same as WSPR, but obviously takes 4 minutes instead
of 2 minutes for a message.
It does seem that there is a 3 dB gain with each doubling of the length
of the message.
WOLF remains the best weak-signal text mode. A WOLF message sent at the
same power level as a just-above-the-threshold Opera32 signal decoded in
3 minutes, 10 seconds, instead of Opera's 32 minutes. Late-afternoon
fading prohibited any further tests, but WOLF should have at least a 3
dB advantage. Disclaimer: WOLF normally requires an SSB exciter and
linear PA.
All in all, Opera does seem to be very useful, especially because of the
simple transmitter requirements. Since all of these tests have been done
in quiet, daytime winter conditions, they don't include the results of
nighttime fading and t-storm static. More to do!
John, W1TAG/WD2XES
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