[RTTY] MMTTY, permanently disable AFC

[David G3YYD]

Tim

MMTTY moves the tone frequencies under its AFC system. 2Tone leaves the tone
frequencies as they are and then uses the AFC value to offset to where the
signal is. It also limits the AFC value to a maximum of 60Hz. One big
problem as you know with MMTTY is it can wonder very far from your intended
tone frequencies.

Turning off the AFC (use the button) and 2Tone is using the set tone
frequencies with no offset. Yet the AFC system still works to show you where
the signal is so you can tune the signal to the set tones. In this case the
small vertical markers are yellow when AFC is on and White when AFC is off.

At the moment 2Tone will only respond to Net on/off commands from N1MM. It
is essential to have Net off when Running so your TX frequency does not
wonder and Net on for S&P so you transmit on your receiving frequency.

While testing N1MM+, I have enhanced 2Tone so that AFC and Net can be
controlled from N1MM+ and Ham default sets the AFC offset to zero. I intend
to release this version of 2Tone when N1MM+ is released.

73 David G3YYD




-----Original Message-----
From: RTTY [mailto:rtty-bounces at contesting.com] On Behalf Of Tim Shoppa
Sent: 17 June 2014 13:14
To: rtty at contesting.com
Subject: Re: [RTTY] MMTTY, permanently disable AFC

Joe writes:
> This limits AFC so it will move *no more than 70 Hz* (.4 x 170). That 
> will allow AFC to "fine tune" but not cause you to go chasing all over 
> the band. Thanks to G3YYD for the idea <G>.

Thanks Joe, I think you hit exactly on my objection to MMTTY AFC. It somehow
gets turned on, then next thing I know, MMTTY's center frequency has
wandered way out of the passband and signals that sound fine to my ears are
not producing the crosshairs in the X-Y and I'm wondering if I had a wire
broke or Windows locked up or something.

2Tone AFC seems much more reasonable, it's like it has a rubber band that
drags AFC back to nominal center frequency rather than letting it wander off
into hyperspace with no return.

All that said I am still more comfortable with using RIT to decode
off-frequency callers when I'm running, than relying on AFC.

I'm not ready to give up on MMTTY :-). I find it often decodes better than
2Tone in contest conditions and am most comfortable when I have both MMTTY
and 2Tone decoding.

Tim N3QE
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