I was pondering this very subject this morning.
Perhaps for the very tightly time-constrained modes a simple computation
comparing the received delta-T's of all received signals could be made. If
everyone else's clocks seem consistently wrong, maybe it's you!
An indication of that made by turning the time readout red, perhaps, or by
having an option to allow that derived time offset to be used to correct the
clock time.
A bit more convoluted solution would be to have a new 'time set' mode that DSPs
one of the WWV signals. We're dsp and radio nerds, right? :-)
A simple C/C++ ntp client could also be included either as an ancillary program
that could be exec'd or built in to the GUI. There are some that are quite
simple - less than 100 lines of code. They're crude, yes, but we're not looking
for sub-mS precision here.
On Jul 23, 2017, at 06:06, Bill Somerville
<[email protected]<mailto:[email protected]>> wrote:
On 23/07/2017 07:48, Mark Turner via wsjt-devel wrote:
± 1.5s shouldn't present a problem to anyone, even, just about, for people
(e.g. some dxp) that rely on crude GPS NMEA serial data time synchronisation.
In the (unlikely?) event that an even shorter DT window is ever considered, I'd
like to request that a small range of DT adjustment be made available -
similar, but perhaps of a smaller magnitude/finer resolution, to JT65's Dsec
setting in WSJT10 (not available in WSJT-X?). Other than using NMEA data,
another scenario where *really* tight timing requirements will cause a problem
is in the use of remote radios where the client software is running at the
remote, not the radio end; obviously there's an inherent, known, and fixed
delay in such a system that can be of the order of 100's of ms.
Regards, Mark
Hi Mark,
all understood. It is clear that FT8 with 15s T/R periods and very short
inter-message gaps has reached the limit of both human response time and
reduced sensitivity that would be acceptable for weak signal amateur radio
operation. I suspect that tighter time synchronization requirements will not be
expected. Everything works against the human speed operator as the limits of
timing are approached, clearly the computer can do much better if it only has
mundane algorithmic work to do but at some point this has to be about the human
getting enjoyment from a hobby!
Achieving +/- 1.5 second clock accuracy is possible with simple aural
comparison and manual update from an on-air time source if necessary. The real
problem is the appalling time inaccuracy of PC systems unless they are helped
by on line time servers, even worse because Microsoft fell that a time update
is only necessary once per few days.
73
Bill
G4WJS.
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