I find Chen's lessons on the sound science behind RTTY very refreshing and very
often there is something new I learn from them. The latest one is his analysis
of using a dash between to separate 599 and the exchange(s):
http://lists.contesting.com/pipermail/rtty/2013-February/038940.html
Long time ago I did my own probability analysis, mostly driven by the desire to
decide if I want to get a Canadian call sign instead of using /VE3, and
concluded that I have to keep the transmissions as brief as possible.
So this CQ WPX weekend I decided to see what happens when I switch the space to
a dash. I did so on the 20 m path to Japan as I wanted to see what happens when
the signal is distorted by significant flutter. As the rate was low the
possibility of more repeats was not a concern. Running about 800W into a 5 el
tribander @ 100'
In over 2 hours I did not have to repeat my exchange even once. I decided to
keep the dashes and then went to 40m and 80m and for the next 7 hours I had to
repeat my exchange only a few times, mostly to barely audible stations on the
West Coast and Asiatic Russia. EU rate was as usual. Running a 4 el 40m yagi @
90' and a 80m inv-V @ 85'
This could be due to the placebo effect, but I perceived an increased use of
dashes by other stations. Interestingly, I did not have any problem copying
such stations; in fact, I did not ask a single station using dashes for a
repeat.
One point to note is that I use 4 concurrent decoder windows with 2 MMTTY
profiles and 2 instances of 2-Tone, one with the regular and the other with the
flutter profile. The salient point here is that I don't have to switch between
profiles and can observe the quality of the copy consistently over a long
period of time using different decoders.
So, is this is robust scientific experiment? No, but the empirical data gives
us a good reason to pause and re-think old strategies.
Rudy N2WQ
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