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Re: Topband: how to hear through static crashes?

To: topband@contesting.com
Subject: Re: Topband: how to hear through static crashes?
From: "GeorgeWallner" <aa7jv@atlanticbb.net>
Date: Tue, 27 Mar 2012 13:42:39 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
On Mon, 26 Mar 2012 19:57:32 -0700
  "Robin" <wb6tza@socal.rr.com> wrote:
> Maybe this is a good time to share the techniques we 
>individually find successful for
> hearing through the giant sparks.
> 
Here are my experiences from TX3A (and other low-band 
DXpeditions). On TX3A, for 30 nights in a row, 8 hours 
each, I had the challenge of copying weak signals through 
strong, incessant lightning crashes (especially from 
sunset until about 10:30 local time). With the following 
set up, this is what I found to work best:

Local Set-Up and Conditions: Receiver K3, ANT DHDL (-36 
dBi Gain), No local RF noise, Bose noise cancelling 
headphones (strong local acoustic noise from birds):

I set the AGC to Fast, mostly used the RF gain to control 
levels, and set the IF Filter to 600 Hz. This last one may 
sound counterintuitive, but I have found that: a) setting 
the filter too narrow results in ringing which stretches 
out the effects of a lightening crash, masking more of the 
signal, b) setting the K3's DSP filter narrower changes 
the shape of the CW pulses and makes them stand-out less, 
and, c) somehow the narrower filter settings degrade the 
"understandability" of weak signals. (This last one was 
also confirmed by my DXpedition partner, Tomi, HA7RY, who 
has better ears and can copy CW great.)

One more thing, with the above settings and with weak 
signals, it was absolutely essential to be able to totally 
concentrate during  the crucial seconds when copying a 
call. I found that allowing any thoughts to intrude would 
wipe a call. Usually, with strong signals, you don't need 
total concentration to work without errors. You can think 
of other things, such as: should I change the RX 
settings?, should I try the other antenna?, shift in the 
chair as my butt is getting sore, etc. But with really 
weak signals, any intruding thought would create internal 
"noise" that could cause me to miss a call. I believe that 
learning to concentrate, and to be able to switch off all 
thoughts for a few crucial moments, is as important as any 
DSP filter or or other signal processing "hardware".

I hope this helps,

George, AA7JV
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