[RTTY] Noise with MMTTY...

[Larry L Lindblom]

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 process.

73 W0ETC  

  
On Mon, 22 Mar 2004 14:16:44 -0600 "Charles Morrison"
<cfmorris at bellsouth.net> writes:
> This email originally started out as asking if anyone's seen noise on 
> their
> MMTTY screens when its running, but I've since discovered something 
> and want
> to ask a different question or opinion..
> 
> I reinstalled MMTTY 2 weeks ago to try to get rid of the
> Userpara.blablalbabla error that pops up immediately following a 
> reboot and
> starting Writelog.  Well this didn't fix, so I quit worrying about 
> it since
> I just exit and restart Writelog and then MMTTY will start without 
> the
> error.  More on that later.
> 
> Anyway, while rushing I tried to recall everything that I had turned 
> on or
> off and started clicking buttons.  What I noticed worried me a bit 
> and I've
> found the culprit but am wondering how much its affecting the 
> decode.
> 
> What I noticed was that regardless of what was plugged into the 
> radio, what
> input settings on the mixer control was selected, what anything on 
> the
> computer was set to, was that with absolutely NOTHING connected to 
> the radio
> or the computer, MMTTY's XY scope still showed some sort of NOISE 
> signal.
> Instead of it being a small dot in the middle, it looked as though I 
> were
> receiving static or noise or something.  If I cranked up the input, 
> MIC or
> Line, it actually increased.  Keep in mind that there's nothing but
> keyboard, mouse, power and monitor hooked to the computer.
> 
> Well, I just got to playing around with it and it's the Band Pass 
> Filter.
> Turn it off, the XY scope goes to a little dot, turn it on, and XY 
> scope is
> active, with everything disconnected, irrelevant inputs selected 
> (CDROM,
> Speaker) etc.  Does this mean that there's additional noise in the 
> decode
> loop?  Is this going to affect my ability to decode weaker signals?
> Wouldn't it be better if when there's truly no signal present that 
> the sound
> card is not detecting something?  It would appear as though its 
> hearing
> "something" when the band pass filter is turned on, because the XY 
> scope is
> showing movement.
> 
> What do yall think?
> 
> Charlie
> KI5XP
> 
> 
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