[RTTY] 2Tone vs. MMTTY - Round 2 testing

[Jeff Blaine]

Very interesting, Don.

I wonder how much of a factor the pre-filtering on the rig side is.

A check at some wider bandwidth (500 hz with a flat single standard 
bandpass) feeding the decoder array would be interesting.  As Chen has 
explained, the decoders cannot do their best if the rig filtering is 
invasive.  Problem is, what 'invasive' is has yet to be determined.  Perhaps 
you have found a baseline for establishing that in a practical sense?

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: Don Hill AA5AU
Sent: Saturday, February 16, 2013 2:21 PM
To: rtty at contesting.com
Subject: [RTTY] 2Tone vs. MMTTY - Round 2 testing

Today I decided to make screen shots of 5X8C on 20 meters comparing two 
MMTTY windows and two 2Tone windows side-by-side.

The decoders were set as follows:
MMTTY1 - Fluttered FIR profile, , AGC on, dual peak filter enabled
MMTTY2 - Normal profile, ACG on, dual peak filter enabled
2Tone1 - Normal with Narrow setting
2Tone2 - Normal with Wide setting

When I first found him he was not real strong, say peaking S3-S5. I made 
over 60 screenshots and notes but by then his signal had
risen to S9 with some fades to S3 to S5, but they were not rapid fades like 
at first.

After his signal reached S9, I stopped making screenshots because all 
decoders were doing an excellent job, so I decided to watch
his next 100 transmissions and mark whether or not the 2Tone decodes were 
perfect and MMTTY took a hit, where MMTTY was perfect and
2Tone took a hit, where print was perfect in all four windows and where 
print was not perfect in either one of the 2Tone and MMTTY
windows. Here are those results:

2Tone perfect, MMMTY not perfect - 21 times
MMTTY perfect, 2Tone not perfect - 2 times
Both 2Tone & MMTTY perfect - 65 times
Both 2Tone & MMTTY not perfect - 12 times

Radio was a PRO III with TPF filter enabled and 250 Hz filter. AGC was set 
to MID (this is important). Decoders were set up in N1MM
Logger. CPU usage was running 70-80% because I had DX Labs Suite running as 
well.

Before his signal was S9, I was experimenting with the AGC. In the past, I 
have always used FAST AGC on RTTY, but I'm sure now that
is not the best setting. I read something from G3YYD, either in his 
documentation or in a post to the N1MM reflector, that 2Tone
works best with a slower AGC. Last weekend I used the MID AGC setting for 
the contest. I noticed that 2Tone performed better with an
AGC setting of MID or SLOW and maybe slow was better, but I will have to 
wait to see the screenshots.

I plan on creating a webpage with the screenshots of the 5X8C decodes before 
his signal was S9. He was never really weak but for a
time there were rapid fades on his signal until he got to S9. Then there was 
a CW signal in the ARRL DX Contest that was within the
passband of my filter for a short while (I varied the filter at times and 
turned off TPF in the radio at times too). The CW signal
was 180 Hz away from his SPACE signal. I will try to compose the webpage 
before the end of the weekend.

73, Don AA5AU
http://www.aa5au.com
http://www.rttycontesting.com



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