[RTTY] Re: Noise with MMTTY

Charles Morrison cfmorris at bellsouth.net
Tue Mar 23 10:29:59 EST 2004

Date:	Mon, 22 Mar 2004 18:21:06 -0600
From:	Larry L Lindblom <llindblom at juno.com>
To:	cfmorris at bellsouth.net
Cc:	rtty at contesting.com
Subject:	Re: [RTTY] Noise with MMTTY...
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I can't speak to this issue directly.  However, on the human factors side
people doing signal detection research stumbled across something that is
counter intuitive.  Is it easier to copy a weak CW signal on a quiet or
noisy band?
Many people will say it is easiest to copy CW on a quiet band.  However,
under controlled testing people did a better job of copying a weak CW signal
in noise than when there was no noise.  A demonstration of this on NPR
nearly blew me away.  The played 10 seconds of what to the human ear sounded
like silence but actually contained a very low level CW signal.  When noise
was added in the CW signal was very obvious.  Of course too much noise mask
the signal entirely.
I doubt electronic circuits/software work the same as the human brain.  But,
the next time you operate the original digital mode don't cuss any noise for
it might be help your brain detect a signal that it otherwise might not
73 W0ETC


Im gonna give you some credit there.  Im sitting here, copying 9A80Z right
now, he's about an S-nothing, and I have to say, of course beauty is in the
eye of the beholder, however, the XY scope while copying him, is still
printing, however the size and form of it actually IMPROVES when the BPF is
turned on, and we know that when my BPF is on, there's additional "noise" in
the loop.

Of course, this could be cosmetic and it could be copying exactly the same,
however without the BPF, even pumping more signal into the soundcard doesn't
form the XY circles as well when its on.. so regardless of noise or not, it
appears to be rx'ing better with it on then off.  Now im totally stumped.


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