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[CQ-Contest] Contest ears

Subject: [CQ-Contest] Contest ears
From: tree@kkn.net (Tree N6TR)
Date: Wed Mar 14 09:35:39 2001

One of my non-contest activities has been hanging out on six meters.
As it turns out, it is possible for a single yagi station on six
meters (albeit a pretty big yagi) to hear signals off the moon.

Recently, while trying to work a station on the east coast (WA4NJP),
I made a recording of a moon echo that has had some interesting
results.  If I play this recording here at work - most people
can't hear the echo.  However, most of the contesters I play it
for can hear the echo.  Obviously, those who have spent a lot of
time listening to weak CW signals have developed better "DSPs"
inside their brain.

I thought I would let y'all have a crack at it and see what you
think.  Perhaps this is one of the many skills that the successful
contester needs to develop.

You can hear the 4 second sound clip at
http://www.kkn.net/~tree/ratrat.wav.  You will hear RAT sent
followed by the echo off the moon.  I think it is best if you can
listen with headphones at a LOW volume.  It seems that the ear
has an easier time with it then.  You might also just want to listen
to the second half a few times to pick the echo out.

It might also be interesting to note that the bandwidth used in
the receiver is 2.7 kHz.  I find this filter setting to be more
effective for EME signals than the narrow settings.  This might
seem counter-intuitive.  Not everyone agrees with this technique,
but many do.  It seems that the brain has an easier time picking
out a weak signal if there is a wide band of noise for it to
compare against.  There probalby are some experts out there who
can explain this better than I can.

This echo was recorded with the moon around 8 degrees of elevation
using a 7 element yagion a 37 foot boom at 45 feet.  The transmitter
output was 1500 watts.

You can hear some other sounds at my six meter EME page at

73 Tree N6TR / K7RAT

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