CQ-Contest
[Top] [All Lists]

Re: [CQ-Contest] FT8 vs FT4 in the Contest

To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] FT8 vs FT4 in the Contest
From: Richard Ferch <ve3iay@gmail.com>
Date: Tue, 3 Sep 2019 16:16:07 -0400
List-post: <mailto:cq-contest@contesting.com>
The operator of WSJT-X does, in theory, have complete control. At any time
the operator can override the automation and decide what to send next. The
problem is that there is only a second or so between the time the program
decodes transmissions in a receive cycle to the time your own transmitting
cycle begins (whether you want it to or not - everything is rigidly
synchronized to the clock - if your computer's clock is off by a couple of
seconds or more, your signals won't be decoded and you won't decode anyone
else's transmissions), and in many situations that simply isn't enough time
to make the necessary decisions and take the correct action. That is why
the automation is there in the first place. The software detects which of
the half-dozen available canned messages it just received and chooses the
appropriate canned message to send in reply, without the necessity for the
operator to decide and act.

In theory, in addition to the half-dozen canned messages, there is also a
"free format" message of 13 characters, but there simply isn't time in the
normal course of a QSO, especially in FT4, to use that in any way other
perhaps than as a pre-programmed 7th canned message (rarely used except
maybe at the end of a QSO). Each transmission cycle in FT4 is 7.5 seconds
(FT8 takes twice as long as FT4, but can decode weaker signals, which gives
it an advantage in some situations).

There are a couple of different operating modes in WSJT-X: normal QSO mode,
which takes a total of 6 transmission cycles (3 from each station) to
complete a QSO, and contest mode, which eliminates the signal report
transmissions and completes the QSO in 4 cycles. If someone operating in
normal mode tries to make a QSO with someone operating in contest mode, the
normal mode software never detects a signal report, which is its cue to
move on to the next step in the dance, so it just repeats the last
transmission (in effect, saying AGN? without the need for a separate AGN?
canned message type). If the operator at the contest station: (a) realizes
that they have the option to exercise manual control' (b) recognizes what
is happening; (c) figures out which message to send to satisfy the software
at the other end; and (d) presses the right button to send the right
message, then they can resolve the impasse and complete the QSO. Or, they
can try to switch from contest to normal mode mid-QSO, but this is not a
simple operation (you have to dive down through menus and windows to find
the switch). So, in many cases they probably just blew away the QSO.

All of the above is assuming good copy at both ends. Now add in missed
decodes (decoding is basically all-or-nothing, either the entire
transmission is decoded or nothing at all), QRM and multiple callers, and
things can get somewhat confused.

73,
Rich VE3KI


KK9A wrote:

I have never operated FT8 or FT4 but I have enjoyed reading about the
recent contest. It appears that there are some things that the FTx operator
has no control over such as saying this was a good QSO and moving on. I
read of instances were the automated software just keeps sending the grid
over and over waiting for a confirmation. Is this correct? In other modes
including RTTY the operator has complete control over what is sent and
logged. It is also interesting that two different versions of FTx were used.
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest

<Prev in Thread] Current Thread [Next in Thread>