> Well, I was thinking about a more detailed explanation of how it
> works.
>
> Think the reflector would be interested also.
I thought for a second that I was going to have to remember WAY back
to the days when I wrote the first English language MMTTY help files.
Thankfully the current help team has addressed this quite well...
"...
turns on the DSP audio notch filter. You can use this feature to null
out a nearby mark or space signal, or a tuner-upper. Here is how it
works:
The notch can be adjusted on the Option | Setup MMTTY Demodulator
LMS/NOTCH tab.
The Not. button turns on the notch capability, but when you first turn
it on, the notch does not appear.
Put the mouse cursor on the FFT display to the far right, and
right-click. A small triangle will appear at the cursor location. This
is the notch center. The notch can be moved around using point and
click.
To remove the notch, press the Not. button again. The next press of
Not. will cause the notch to reappear.
You can set two notches on the Option | Setup MMTTY Demodulator
LMS/NOTCH tab. The tabs alternate with clicks. That is, set the first
tab with a right-click, and the next right-click sets the second tab,
while the first one stays in place.
. Each triangle indicates the center of the notch filter. Note that
the signal is strongly attenuated at that point.
Note: A left-click of the mouse cursor moves the passband, while a
right-click sets the notch.
BPF
BPF stands for bandpass filter. It can be adjusted at Option | Setup
MMTTY Demodulator BPF tab. This DSP filter is centered on the middle
of the bandpass shown in the FFT, so all you do is turn it on and off.
The usual setting for BPF is on, so MMTTY can decode well in the
presence of an interfering signal
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