[RTTY] Noise with MMTTY...

[Charles Morrison]

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