[Moon-net] Time syncronization on JT65

[Edward Cole]

Joe,

In the beginning of using JT44 and then JT65 I did not fully 
understand or use all the features of the program.  Offset of DT is 
in that category as quite a few of the "I am getting a strong signal 
but no decode" can be traced to a time offset.  On many a eme contact 
I was able to enter a small time offset to solve the "does not decode" issue.

I hope JT65 users out there are reading your words.  One feature I 
have not had any success with is "zap".  I'm ready to know the secret 
of how that works.
Thanks, Joe.  WSJT has revolutionized eme for me.  My deterioration 
of hearing makes CW about 10 times harder these days.  JT65 evens it 
out for me.

73, Ed - KL7UW

At 08:07 AM 4/19/2007, Joe Taylor wrote:
>Hi Cris, Alberto, and all,
>
> >>Let me put in another way. If a hamradio from Mars will intend to work
> >>randomly with a hamradio from the earth using JT65 than they couldn't
> >>because they will not have the same clock standard as a reference except
> >>if they use an atomic clock. GPS is not working...
> >
> > Oh, they could use a synchronization based on some Pulsars...
>
>Yes, synchronization of a digital mode using pulsar signals
>would be quite feasible.  :-)
>
>However, as Leif/SM5BSZ has pointed out, there is no need to
>do this.  The decoding software can "search" over time just
>as easily as over frequency.  WSJT does this already for the
>JT65 mode, searching over a 12-second range (from DT = -2 s
>to DT = +10 s).  It would be trivial to extend the search
>range to a full minute, if there were any reason to do so.
>
>In some recent evenings I have been amusing myself as an SWL
>on the HF bands, copying the large number of JT65 signals
>that now appearing there.  Occasionally a new operator fails
>to appreciate the need to set his computer clock, so his
>transmissions are mistimed by random amounts of 20, 30  or
>more seconds.  Such transmissions are still very easy to
>decode; one simply needs to watch the waterfall, see where
>transmissions start and finish, and offset the WSJT clock
>(using "Dsec") by the amount necessary to achieve
>synchronization.  It's easy to do, since the WSJT search
>range is already 12 seconds long.
>
>         -- 73, Joe, K1JT
>
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73,
Ed - KL7UW
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