I think the distinction needs to be made between passing traffic and a
QSO. No matter how fast a typist you may be, or how fast the mode is,
unless you "typeahead" at a furious rate, the amount of time spent
typing thoughts, or during changeovers, is the same if the mode is 50
wpm or 250 wpm.
The other problem is that wide modes "tend" to have a poorer minimum S/N
than more narrow modes. I am not sure why this is true, but it is for
almost all the modes at our disposal. Double the speed, and you double
the bandwidth, but require two times better S/N. Perhaps if a wide mode
were designed that effectively used all the bandwidth as effectively as
a more narrow mode, this would not be true. There is probably
communications theory to tell if this is possible.
Just suppose all the PSK31 operators switched to Contestia, which works
better than PSK31 under adverse conditions. There probably would not be
enough space on HF to handle all the QSO's now on PSK31. Sure, there
would be less fills or errors, but many people are satisfied with the
PSK31 performance. However, there is a case to be made for using Olivia
or Contestia 16-500 (30 wpm in Contestia or 15 wpm in Olivia) -
communication is simply possible when it is impossible using PSK31, for
example on UHF where Doppler effects make PSK31 totally unusable, or
over the polar path.
There were 3 S-units of enhancement two days ago on our UHF path, and
very little Doppler, so we tried PSK125R. No problem at all, and no
errors, but you type for a minute and it all goes out in a few seconds,
and then you wait for the other station to type for a minute, etc.! It
is just essential to define the purpose of communication - is it for
passing traffic as quickly as possible, or is it for conversation? The
choice of mode and speed depends upon the path and purpose and there is
no clear choice that fits all.
For us on UHF, we find that Contestia is every bit as good as Olivia,
but twice as fast (at 30 wpm) when Olivia seems painfully slow for
comfortable conversation at only 15 wpm. I touch-type at only about 35
wpm, and if I make a typo, many times there is time for me to backspace
and make a correction just before the letters are sent out, so Contestia
is a good "fit" for me - sensitive, fast enough, and resilient to the
rough conditions we have on UHF. Olivia might be a better "fit" for
others and have both upper and lower cases. BTW, in the latest fldigi,
there is an option to print incoming text in all lower case, which some
find easier to read for conversation than all upper case. Transmission
is converted to all upper case, of course.
73 - Skip KH6TY
Andy obrien wrote:
I agree Skip. Recently I used fldigi and PSK250 on HF. After
emptying what few macros I had , I was reduced to typing with my two
fingers. A rag-chew QSO with something as fast as PSK250 was a waste
of effort. By the way, I pass perhaps 1-2 messages per week with
WINMOR nowadays. When connecting to a "server" that is set for 1600
Hz rather than the alternative 500 Hz, I rarely notice any better
through-put. The wider mode just takes up more spectrum.
Andy K3UK
On Sat, Apr 17, 2010 at 6:17 PM, hteller <[email protected]> wrote:
Brian,
I often hear people talking about preserving bandwidth and I wonder why
that is such a goal? Sometimes increasing bandwidth can improve performance
to the point where you get all the bits through in a shorter period of time,
making the channel available to others. Think about spread-spectrum or
packet radio vs. RTTY for example.
This the argument that Winlink tried to foist upon everyone over five years
ago when asking for unlimited space. The fallacy of that argument is that
the frequency (or channel) is dominated by one station that keeps the
channel occupied until "its" traffic is passed, whereas, if more stations,
say five, can fit in one of our limited frequency ranges and pass traffic
simultaneously at only 1/5 the rate, the chances of more than one station
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