[Lowfer] LEK - BRO Wrapup [Long]

[John Andrews]

Since last week, LEK has been transmitting in WOLF mode, 50 Hz above or
below BRO, who has continued to send QRSS60. Both stations are in MN, on the
same loop bearing for me, and at a distance of about 1100 miles.

I have been comparing the signals as recorded from 0230 to 0630 EST
(0730-1130 UTC), which has been the best time period for that path over the
last year. I have only rarely copied either station during the evening
(pre-midnight) hours. Lyle has observed that the E/W paths tend to be less
productive than N/S paths, and that pretty much squares with my experience.

In reading a QRSS signal with software like Argo (which I used), the brain
becomes a big part of the process. On seeing a broken line exactly on
182.200 kHz, I can reasonably assume that I'm seeing BRO, and then try to
figure out what's being sent. Since Bryce has been sending "BRO", I only
have to guess one of three letters. Sometimes that's not possible -- only
fragments are present. You "know" you are copying BRO, but it would be tough
to prove it to others.

On the face of it, WOLF is less vulnerable to a runaway imagination. Unless
the signal is being correctly decoded, you only see endless permutations of
the alphabet. I have in fact seen some of the words I spoke aloud on
realizing that conditions were really bad! But there are a lot of clues in
the numeric data in the WOLF output, the most important of which is the
apparent frequency. Just as with BRO, I KNOW that LEK is on frequency. I'm
not going to waste my time looking farther than 0.1 Hz from Lyle's announced
spot. And once having correctly decoded LEK, I can watch for that particular
frequency on later files. This allows you to say that the signal "is there,"
even though WOLF isn't decoding it correctly.

With a few exceptions, during the last 6 nights, if I could say that BRO
"was there," LEK was also, using the above criteria. The exceptions probably
trace to interference. WOLF occupies a much larger bandwidth than QRSS60,
and while you benefit from the mini-spread-spectrum nature of it, WOLF can
be clobbered by a signal that your brain would ignore in QRSS mode.

There were a number of instances where BRO could be legitimately copied with
clearly readable characters, and LEK just wasn't decoding. As many have
observed before, there is a threshold for WOLF. I've found that the "q"
values are a big help in anticipating what's going to happen. Copy is likely
with values above -3, though last night there was one file where it was
at -2 with no luck.

When WOLF copy is possible, you get 15 characters. If you only got one
correct line in the full 27 minute, 10 seconds it can handle, you would only
have received 13 more characters than you would for a QRSS60 signal. If you
receive multiple lines, as is common, you have lead-pipe-cinch confirmation
of correct copy.

QRSS -- 60, in this case, would be my choice both for simplicity, and for
the ability to identify a station as being receivable. With our 2 or 3
letter call signs and a reasonbly active imagination, it would be the weak
signal mode of choice for most current Lowfer activity.

WOLF has a clear advantage for moving more information in the same amount of
time, and should be workable at the same signal levels that produce
"correct" QRSS60 copy. If it only decoded in real-time, it would be much
more valuable mode for 2-way QSOs. As it stands, with fast computers at each
end, and a short transmit/receive switchover, QSOs  with "real" information
should be possible. Dex and I attempted it once, but my transmit antenna was
not up to the task. Note that with my new 1.6 GHz P4, a full-length WOLF
file takes 1 minute, 50 seconds to decode. Neat.

Thanks to Lyle and Bryce for the signals. If anyone has any opinions, pro or
con, please weigh in!

John Andrews, W1TAG