Hi Russ,
some comments in line. BTW I don't operate EME so these are based on
looking at the source code alone.
On 15/12/2018 00:33, Russ wrote:
I'm having a lot of problems using JT65 for EME. The right hand pane,
Average Decodes, seems to have a mind of it's own. For instance, earlier I
was trying to work N5TM and I did copy two of his sequences. Now, an hour
later I am just sitting here watching the screen and suddenly in the average
pane a new message from him pops up. It has the same text as the previous
decide but it has the current time and the dB, Dt, and frequency vary. As I
watched for 15 minutes that same message popped up 8 times. There are no
signals showing in the waterfall and I am positive that he is no longer
transmitting to me - also there is nothing showing in the right hand pane,
Singe Period Decodes.
That is one manifestation of the problem. Another is somewhat similar.
About 3 days ago I decoded but did not work a station in France. Since then
that same decode pops up randomly in the average window even though I am
currently working someone else. Not only is he not transmitting to me, and
the moon is not up there, but it has been 3 days and WSJT-x has been shut
down and restarted several times and has been used on MSK144 extensively for
Geminids meteor activity. Yet when I switch back to JT65 it still remembers
and displays that old decode !
Do you click the "Clear Avg" button after you are done with a QSO?
Another thing that happens is that sometimes when I get a single period
decode of a station that I am working, it will immediately appear twice in
the average window.
Are the two lines identical?
I don't know if anyone else has seen that problem, but I cannot figure out
any way that it could be my setup. Windows 10 Pro.
One more thing. It is most disconcerting when in the middle of an EME
contact, to discover that you are no longer transmitting. I think the time
out timer should be able to be disabled when in JT65. Or removed - like in
older versions of WSJT.
You can disable the Tx watchdog timer yourself in "Settings->General"
set the value to "Disabled" (it is below 1). Another thing others find
useful is to use different configurations for different modes and bands
("Menu->Configurations"), this allows you to preset the settings you
desire for a particular mode of operation.
While sitting here typing this message my average decodes pane has
completely filled with red messages from N5TM: 0028 -30 -3.2 201 #* K2TXB
N5TM EL29 ? d20
What's up?
Once the message averaging is weighted close to a near good decode it is
likely that random noise will eventually complete the averaged decode.
Judicious use of the "Clear Avg" button is needed to keep things sane,
for example if you know your QSO partner has finished transmitting or
changed to the next message then give the averaging a hint and clear it
down. The JT65 code does not include a checksum (FT8 and MSK144 do) so
the decoder can only verify a potential decode is good by it being self
consistent (there are a couple of pathological cases like blank decodes
that are discarded), whether it be off air alone, and averaged sum of
receptions, or weighted by a deep search. There is no secondary
information to confirm the decode other than your judgement. The JT65
decoder, at its root, simply takes a statistical view of the signal
energies at each symbol's point in time (determined by the detection of
and alignment to the detected synchronization clock). There is no
certainty, just a high probability the decode is correct. Averaging only
makes sense when you are confident that it is being fed with real signals.
Thanks, Russ K2TXB
73
Bill
G4WJS.
_______________________________________________
wsjt-devel mailing list
wsjt-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/wsjt-devel
