MMTTY AFC, O-scope (Re: [RTTY] Re: Noise with MMTTY

[Don Inbody]

In the Navy, when we used RTTY extensively, it was 850Hz shift, 100 baud.
Of course, we also had the signal encrypted, so that required constant
"diddling" to ensure the crypto remained synchronized.  

My question is this: is there any proof that narrow shifts (170Hz for
example) is better than wider shifts (850Hz) for resistance to phase
shifting.  Also, what is the history as to why we settled on 45 baud 170Hz
and not some other.  I know a lot of experimenting went on in the 1950s and
1960s, but can't seem to locate the data.

I did an experiment with 850hz shift the other night, but can't see that it
is any better or any worse.

Just curious,

Don

Don Inbody/AD0K
QSL via LotW and eQSL

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On
Behalf Of Bill Turner
Sent: Wednesday, March 24, 2004 10:41
To: RTTY at contesting.com
Subject: Re: MMTTY AFC, O-scope (Re: [RTTY] Re: Noise with MMTTY

On Wed, 24 Mar 2004 10:06:33 -0600 (CST), Peter Laws wrote:

>Speaking of the virtual oscilloscope ... When someone is transmitting with
>a shift of other than 170 Hz, I've been tuning so that the vertical bar is
>vertical (which means that the other bar is not quite horizontal).  Is
>that right, or should I tune so the horizontal bar is actually horizontal.

_________________________________________________________

I split the difference, tuning so the bars (ellipses) are equally "off".
Seems to work ok as long as they don't exceed 200 Hz by much.

It seems that the 200 Hz'ers are slowly disappearing, but it's a mighty
slooooooow process.  :-) 

--
Bill, W6WRT
QSLs via LoTW

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