Interesting discussion, though I don't exactly know why this veered off into
what modes are "better" contesting and how to hack MMTTY for 7 bit ASCII. This
thread was about PSK31 being less fun than RTTY in FD because it was too slow.
I don't particularly care if someone includes a SITOR-B in their contest like
the RTTY Roundup or strictly 45 baud Baudot (apparently 45.45 baud allowed--I
may risk the DQ and crank it up to 46.0 baud this year). As far as I'm
concerned it is up to the contest sponsor define and then the operators to
decide how to maximize score (or fun). This was initially about the perceived
lethargy of PSK31.
Anyway, thanks to those who were willing to check math--the back of the
envelope is not a spreadsheet :-) Chen pointed out that PSK31 actually uses
what is effectively two stop bits for character synchronization (ouch, but it
does make writing a demodulator much easier). The updated tables are at the
bottom of this message. I also changed the messages to have a leading and
trailing space, since this is maximally efficient in both modes and is an
accepted practice in the RTTY world. RTTY is still calculated using USOS.
That's probably as "apples-to-apples" as we can get.
The important part for our discussion is that the FD exchange tends to break
even with 45 baud RTTY--its a little faster than RTTY if you are in NE and a
little slower if you are in WCF or your callsign has lots of Z's and X's, but
certainly not significantly slower on the whole. As has been mentioned in the
thread, the ARRL FD exchange is expensive in RTTY due to all of the LTRS/FIGS
shifts from which no contortions of USOS can save you. If operators would send
lowercase and keep out the unnecessary punctuations and emoticons,
PSK31--especially in FD--shouldn't be slow because of the nature of the
encoding and lower bit rate.
So where's the beef? Paul, N8HM, mentioned the preamble and squelch tail that
seemed to waste time. I listened to about 10 minutes of 20m that I recorded
Saturday evening. Having never used PSK for short exchanges, it was never
something I paid attention to. With half the transmission eaten up by the
squelch opener and squelch tail with no print, I can sympathize. The
demodulator probably needs a short sequence of 0's in PSK31 to get sync, but
apparently the software out there sends the sync sequence for about a second,
which has to be way more than necessary for character synchronization--I would
think you would need only a few for the demodulator to get the timing. This is
really no different than the mark tone before the first character on RTTY--a
mark-space transition to know where noise ends and signal starts and will
probably help the demodulator find that first start bit. The squelch tail on
PSK31 is apparently intended to be a way turn the reciever off so that it doesn
't print noise when there is no signal. This is pointless in a contest, and
other than unattended reception of the ARRL QSTs, I wonder what purpose this
It seems to me that the real annoyances stem from ancillary "features" that get
in the way. If someone cares enough, perhaps he or she would petition the
software developers to make more contest friendly features for PSK31. I know
several watch this list. It seems to me that if a sponsor is going to have a
PSK31 contest, why not actually make it more fun by having a software
configuration that makes it so. Maybe we'll have something for the next FD?
What better place to to set a good example and do some on-air education?
Just inferring from comments on this reflector, here's perhaps a starting point:
A) Short synchronization sequence
B) No squelch tail. Maybe force a space at the end the transmission.
C) Force sending in lowercase by default
D) Option to print received text in all caps
I imagine some of these would be pretty easy to do, but I learned long ago
never to estimate another developer's effort level or desire to do some work :-)
Here are the corrected tables:
Bits(P) Bits(R) PSK(s) RTTY(s)
_cq_k0sm_k0sm_cq_ 123 157.5 3.94 3.47 -13.58%
_cq_aa5au_aa5au_cq_ 147 172.5 4.70 3.80 -23.94%
_aa5au_andy_ny_ny_ 111 150 3.55 3.30 -7.63%
_aa5au_4a_ne_ 82 127.5 2.62 2.81 6.46%
_aa5au_599_678_ 125 142.5 4.00 3.14 -27.58%
Here are a selections of callsigns (not including surrounding spaces). John
gets a heavy penalty by the varicode, but not as bad as on CW.
n6ee 25 45 0.80 0.99 19.20%
aa5au 37 52.5 1.18 1.16 -2.50%
k0sm 35 45 1.12 0.99 -13.12%
4x6z 43 60 1.38 1.32 -4.23%
wa5zup 51 60 1.63 0.99 -64.83%
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