Our big storm was as severe as expected. The two large cities closest
to me, Philadelphia and New York, are basically shut down. I am without
power at home, and will probably remain so for some days. I write this
message from my Princeton University office.
I have posted an installation file for WSJT-X revision 2706 on the WSJT
web site. The link for direct download is
http://physics.princeton.edu/pulsar/K1JT/WSJTX_02r2706.exe
Changes since r2702 include the following:
1. The problem with "ghost" signals is fixed.
2. A problem causing very long decode times under certain circumstances
has been fixed. Please note: decode times on any recent PC should no
more than a few seconds!
3. I have re-directed the program's fatal error messages so they will be
sent to the command-prompt window from which you started the program.
Please send me full reports on any such messages you observe, preferably
with details on how to reproduce the problem.
#########################################################################
Some additional information ...
1. Yes, the JT9 modes require good stability in all system oscillators.
The present JT9 bdecoder does not attempt to track frequency drifts.
Such capability will be added, however. We have been using digital
modes for EME for nearly ten years now, at 144 MHz and higher. There
are more than 1000 WSJT users on EME, using all kinds of rige. We have
learned how to deal with reasonable rates of drift. Surely if we can do
these things at VHF, we can do them much more easily at MF and LF.
2. If you're sure that you have seen degraded JT9 performance because of
frequency stability issues, don't just complain on the LF reflector.
Document your case and send me an example file with a drifting JT9
signal. Making WSJT-X and JT9 better is partly YOUR responsibility!
3. In other ways as well, test files are needed. I can make many tests
myself, but I can't foresee all the problems others will have. That's
what the "Save All" function is for! In these early tests, always run
with "Save All" checked, just in case you will want to refer back to
something that happened. You may want to send me the file in question.
You can always clean out your "Save" directory by using "File | Delete
all *.wav files in SaveDir". I need good examples of signals that fail
to decode for any unknown reason. Also some good examples of
atmospheric or other impulsive noise, for testing the noise blanker.
4. I have added a page of "Hints for New Users" to the online WSJT-X
User's Guide,
http://www.physics.princeton.edu/pulsar/K1JT/WSJT-X_Users_Guide.pdf .
Please read it! ... and let me know if you find other operational
details of WSJT-X that need explanation. This will likely be especially
true for those not already familiar with older versions of WSJT.
5. An operational suggestion: In many ways the different JT9 submodes
are treated as distinct modes. If you receive a JT9-x signal in a
different submode than the one you have selected, you won't decode it.
For this reason, if JT9 is to become popular we'll probably need to
choose one or two of the submodes for general use, and perhaps assign a
narrow slice of the band to each one. Note that "message averaging" in
the Rx software can make two or three JT9-2 transmissions as good as one
JT9-5 transmission, with the advantage that you will copy sooner if
signals are better than required for JT9-5. Message averaging is not
yet present in the JT9 decoder... but in future it can be. Again, we
have dealt with such issues very effectively on EME -- and can do so at
MF/LF, for sure.
6. On the topic of CW, Beacons, WSPR, JT9, etc. I really don't
understand what all the fuss is about. Surely there is room for
everybody? Maybe I'm just too new here to understand? (Mal, is this
mostly just a matter of "Mal being Mal"???)
On the HF bands, the WSPR sub-band is just 200 Hz wide. If we did the
same on 630 m, the WSPR sub-band would take up less than 3% of the 7 kHz
band. If that's too much, we could cut it in half, or even less, and
still have enough WSPR space. Moreover, a "slow WSPR", if warranted,
would require even less bandwidth. Similar comments apply to JT9. The
bandwidth of JT9 signals is significantly less than that of CW, for
comparable information rates. There should be enough spectrum for both,
even in our narrow MF and LF bands.
7. As for performance comparisons between JT9 and WSPR: WSPR is a mature
program, and its decoder has been optimized and tweaked over a period
approaching five years. You are playing with JT9 in infancy. With help
(as opposed to simple complaints) from users, it will improve rapidly.
That's all for today! Here's hoping that we get power restored before
too long, and that other aspects of this weather disaster will in time
be manageable.
-- 73, Joe, K1JT
