[RTTY] A challenge to RTTY operators!
chen at mac.com
Thu Nov 15 12:52:16 EST 2007
On Nov 15, 2007, at 11/15 9:03 AM, Philip Leonard WVØT wrote:
> For me the "problem" with PSK31 for contesting is that it is slow
> and so
> is hard to get a rhythm going.
One of the the reasons PSK31 feels slow is due to that 1/2 to 1
second squelch tail at the end, where PSK31 goes into idle mode and
then sends a short unmodulated carrier. That is why you hear the
vibrato stop and then followed by a beeeeep at the end of a PSK31
It is easy to get rid of that tail when you are "contest mode." A
single line of code change ought to accomplish it. RTTY contesters
are used to seeing something like this anyway:
599 001 W7AY @#^D$&$*()))G
(that is why it is important to insert at least one space character
after an exchange).
There is no reason not to get rid of the PSK31 tail when contesting.
Of course it is no longer strictly obeying "true" PSK31, if you go by
the specs for that mode.
Also, and I trust regular RTTY contesters already know this fact
before participating in PSK contests, in PSK31 Varicode (and MFSK16
Varicode, for that matter) lower cased characters take a shorter time
to transmit than upper cased characters.
A lower case 'a' uses 6 bit periods (counting the sync bits) to
transmit while an upper cased 'A' takes 9 bit periods (also counting
the two sync bits). Folks transmitting upper cased exchanges will be
slower than those who use lower-cased only exchanges.
This, compared with the 7.4 to 7.5 bits in Baudot -- also counting
the start and stop bits. Some mechanical teletypes use 1.4 stop bits
but most software modems transmit 1.5 stop bits.
Use some of these tricks, and your exchanges will be faster, and you
won't even be accused of using a second radio :-).
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