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Re: [RTTY] 200 hz filter on RTTY

To: aa5au@bellsouth.net, rtty@contesting.com
Subject: Re: [RTTY] 200 hz filter on RTTY
From: "Charlesjr@afgimail.com" <Charlesjr@afgimail.com>
Date: Tue, 1 Jun 2010 13:26:25 -0400
List-post: <rtty@contesting.com">mailto:rtty@contesting.com>
There is actually three carriers on the signal you mentioned. The one in the 
middle is the 
strongest. The two weaker ones about 5hz each side from the middle one. I 
always thought it was a 
harmonic from some commercial station down in the 5.1mhz range. Sometimes you 
can see all 3 
sometimes not depending on condx's at the time and what your rig/software can 
I turned Autotune off in RITTY and had perfect copy with the weak right side 
carrier about 3hz away 
with the PROIII set at 350hz bw. The E4X sig was just a little stronger than 
the weak right side 
carrier with nothing showing on the s meter.
RITTY can also copy single tone rtty, even vy weak ones. Every time I see a 
spur I put the mark on 
it and invert the signal with perfect copy. I have been questioned before about 
spotting rare/semi 
rare dx. One even got on the air and called me a liar when I spotted the T6 
when other W's could 
not hear him. Right after my spot EU jumped all over him and starting spotting 
him. RITTY pulls 
them out of the noise and in some cases you can't even see or hear the signal.
I did not log them on 30M. Maybe next time.

------- Original Message -------
>From    : Don Hill AA5AU[mailto:aa5au@bellsouth.net]
Sent    : 5/31/2010 11:04:15 PM
To      : rtty@contesting.com
Cc      : 
Subject : RE: [RTTY] 200 hz filter on RTTY

 Test driving a new Icom IC-7600 on consignment from Icom.

Tonight there were several us in New Orleans trying to copy E4X on 10140 kHz.  
There was a very 
strong steady signal right on his
mark frequency.  After a while, the carrier moved down about 40 hz.  At that 
time, I implemented 
the 200 hz filter on the '7600 and
the carrier completely disappeared from the passband and I was able to copy 
about 80-90%.

Something else the '7600 that the PRO III does not and that is the notch filter 
works on RTTY with 
the Twin Peak Filter turned on.
Didn't help with the signal when it was right on his mark frequency though.  
Not much you can do 
about that although I have heard
rumors of a modem that could actually copy Baudot hearing only one of the two 
tones, but this could 
have been a HAL myth.

I think I remember someone, maybe Chen, saying a 200 Hz filter would not work 
on RTTY or something 
to that effect.  Maybe I don't
have the story just right, but it appears to be working great.  Too tight for 
contesting, but works 
when required.

73, Don AA5AU

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