Re: [wsjtgroup] If possible...
- Hi Jean,
Many thanks for your suggestions!
There are good reasons for the design choices that set the default JT65
sync tone frequency to 1270 Hz, and the default condition so that "TxDF"
does not automatically track the setting of "Freeze DF".
JT65 was conceived and designed for EME communication at VHF and UHF.
The sub-mode JT65A is used for 50 MHz EME, JT65B for 144 and 432 MHz,
and JT65C for 1296 and 2304 MHz. In the "C" mode the highest tone is
711 Hz above the sync tone; the 1270 Hz default setting keeps that
highest tone well within a SSB transceiver's filter passband.
In EME communication there are many reasons that received values of "DF"
may not remain constant. We are talking about frequencies one to two
orders of magnitude higher than typical HF frequencies, so oscillator
drift is much more of an issue. Even with stable oscillators, Doppler
shifts on the EME path mean that received frequencies don't stay
constant. Unlike typical operation with JT65A at HF, EME operators may
frequently change the setting of "Freeze DF" during a QSO. They do
*not* want their Tx frequency to change after such adjustments have been
You made no particular case for 1500 Hz rather than 1270 Hz, or for
"center, not edge", so I can't evaluate your reasoning. However, I do
understand that the use of JT65A at HF would be more convenient and
better behaved if some default settings were different for HF and for
VHF+. Since the program has a "Band" setting, it should be possible to
use this to "have it both ways", as appropriate for the frequency in use.
I have no idea what fraction of JT65 users on HF are using MultiPSK,
instead of WSJT. That, of course, would be another issue.
-- 73, Joe, K1JT
> If you are planning a new soft for HF use, I should like
> -- transmission centered on 1500 Hz,(center, not edge), not 1270
> --AND BEFORE ALL :
> An auto transceive feature as a default : click anywhere in receive, and
> the tx follows...
> It appears that now one qso out of 2 is in split, and takes 2 freq when
> one is enough.
> Yet this morning, two cq on 14075.75, two answers on 14076... and two
> qso on double freq. Impossible to TxDF on the caller's freq, he thinks
> he lost me !
> With the increasing number of new stations trying JT modes, it happens
> all the time. Many are unable to read the help or do not understand what
> they are reading !
> Best 73.
> Jean F8RZ