Changes in WSJT 5.9.3: January 26, 2006
This is a minor maintenance release.
1. New Help screen provides a list of available suffixes and add-on
2. The occasional error message about "images do not match" has been
trapped and should no longer occur.
3. It is no longer necessary to enter one's own grid locator with the
first two letters in upper case and the last two in lower case.
4. Initialization of the PTT line to the "OFF" state has been fixed.
Changes in WSJT 5.9.2: January 16, 2006
1. Thread priorities have been adjusted for smoother operation.
2. The JT65 decoder has been given improved immunity to garbage data
(birdies, QRM, etc). It exhibits better performance on strong
signals and provides more accurate estimates of their S/N.
3. The FSK441 decoder produces less on-screen gibberish when
processing mouse-picked decodes.
4. The JT6M decoder now makes better use of Freeze and Tol. You can
set the value of "Freeze DF" by using the Right/Left arrow keys.
(This feature is also useful in JT65 mode.)
5. On-screen font sizes can be set by using Windows Notepad to edit
the file wsjtrc.win. If your screen has resolution greater than
1024 x 768, or if you have old eyes like mine, you may want to
increase the font sizes from 8 and 9 points (first three lines of
the file) to, say, 9 and 10 points.
6. A simulator mode is now built into WSJT for testing purposes. It
is presently most useful in JT65 mode. By entering, say, "#-22"
in the text box for Tx6, you signify that the program should
generate its Tx audio files with the signal embedded in white
gaussian noise, 22 dB below the noise power in a 2.5 kHz
bandwidth. You can direct this signal into a second computer
running WSJT, for example to test the decoder or to practice
operating in JT65 mode. You can even have the two computers "work
each other" in a simulated QSO, although changing messages of
course requires operator action.
7. Dividing lines are now provided on the waterfall display between
spectra corresponding to wave files read from disk.
8. The PTT line is explicitly set low on program startup.
9. The F10 key brings up the SpecJT screen (if it was hidden) and
toggles foreground and focus status between the WSJT and SpecJT
10. You can use the Alt-F and Alt-Z keyboard shortcuts to toggle
"Freeze" and "Zap" on and off.
11. "Accelerated decoding" has been removed from the Setup menu. In
effect, this option is now always ON.
12. Text windows are now cleared when switching between modes.
13. Linux and FreeBSD versions (see below) offer PTT control via
parallel port, as well as serial port. They offer sound support
via ALSA and OSS.
1. The use of non-threadsafe code for FFTs could cause occasional and
unpredictable program crashes. Fixed.
2. A bug in the JT65 decoder could (rarely) cause large errors in the
reported level of strong signals. Fixed.
3. The program could be made to crash by trying to read a very short
wave file. Fixed.
4. "Save None" now works as it should.
When entering your grid locator on the Setup->Options page, use upper
case for the first two letters and lower case for the last two. For
example, for K1JT the locator is FN20qi.
For Curious Users, and Especially for Programmers
WSJT is no longer a one-person effort, and the program no longer runs
only under Microsoft Windows. WSJT is now a full-fledged Open Source
project, with an active working group making contributions to future
development. Source code is now stored in a public repository under
control of a version control system called "Subversion," or SVN. You
can learn more at http://developer.berlios.de/projects/wsjt/.
The first significant result of the group effort has been to create
versions of WSJT that run under the Linux and FreeBSD operating
systems. Porting WSJT to the Macintosh platform should be
straightforward, but has not yet been done.
If you are interested in testing and using WSJT on your own Linux or
FreeBSD system, we'd like to hear from you. Please note that the
present Linux and FreeBSD versions are intended mainly for
programmers. You need to know your way around these operating
systems to be able to install them.
If you feel that you can usefully contribute to the future development
of WSJT on any platform, we would also like to hear from you! We
could use help with documentation and website maintenance, as well as
The present WSJT working group consists of:
Diane Bruce, VA3DB
Bob McGwier, N4HY
Jonathan Naylor, ON/G4KLX
Stewart Nelson, KK7KA
Joe Taylor, K1JT
Kaj Wiik, OH6EH
Changes in WSJT 5.9
1. JT65 decoding has been made faster and significantly
improved in other ways. Three new options appear on the Decode->JT65
menu: "Fast", "Normal", and "Exhaustive". The program is most
sensitive if you choose "Exhaustive". Choosing "Normal" will make
decoding slightly less sensitive, but the loss is not great, and
decoding can be twice as fast. The "Fast" setting is faster still, but
can be less sensitive by 2 dB or more in some cases. If you have a 1.5
GHz or faster computer, use "Exhaustive". With a slower computer you
may want to experiment with the other settings.
2. In JT65 mode, double-clicking on the waterfall (SpecJT window) or
on the red curve (main window) sets "Freeze DF" to the selected
frequency, turns Freeze ON, sets Tol to 50 Hz, and invokes the decoder.
Using this feature, you can quickly decode a transmission at several
different values of DF. I find this feature to be *extremely* useful.
3. The range of DT values searched to establish synchronization has
been doubled, now extending from -2 to +10 seconds. The reported
values of DT are more accurate, as well. You should normally expect
EME signals to have DT in the range 2 to 3 seconds, but the program
will now synchronize properly even if DT is well outside this range.
4. WSJT now offers the ability to correct for errors in soundcard
input and output sampling rates. Numbers displayed in the first panel
of the status bar (at lower left of the main screen) give the ratio of
actual sample rates for input and output to the correct value, 11025
Hz. The numbers should stabilize within about one minute after program
startup. If they fall in a "safe" range between about 0.9990 and
1.0010, you have a good sound card (at least in respect to sampling
frequency). You can then leave the entry fields "Rate In" and "Rate
Out" on the "Setup -> Options" page at their default values, 1.0.
If your soundcard gives one or both numbers well outside the safe
range, you should enter the displayed errant numbers as "Rate In" and/or
"Rate Out" on the Setup->Options page. This needs to be done only once;
subsequent changes in the last decimal place of the displayed values
are not very significant, and can be safely ignored.
The result of this procedure is that your Tx signal will be "trimmed"
so that your tone spacings in time and frequency are more nearly
correct. In addition, your digitized Rx signals will be adjusted so
that the software can properly interpret them.
This trimming is an important procedure. Some recent sound cards
produce sampling error factors as low as 0.9932 or as high as 1.0068.
If uncorrected, such results can degrade your S/N in WSJT modes by 2
dB or more.
If one of the measured sample rates differs from the corresponding
value specified for "Rate In" or "Rate Out" by more than 0.1%, a red
warning label will appear just below the graphical area on the main
5. The graphical display of information obtained during JT65 decoding
has been enhanced. As before, a red line illustrates the maximum
correlation between the pseudo-random sync tone pattern and the
received signal at each value of frequency offset, DF. A blue line
shows the correlation at the best DF, plotted as a function of time
offset, DT. If a shorthand message is detected, two new lines colored
magenta and orange replace the red and blue lines. The new lines
illustrate phase-resolved spectra measured in each of the two phases
of the shorthand square-wave pattern. A properly detected shorthand
message will show a peak in the magenta curve, followed at a specified
distance by a peak in the orange curve. The correct
locations of the two peaks are marked by small yellow ticks. Unlike
the alternating shorthand message tones, birdies will appear with
approximately equal amplitudes in the magenta and orange curves.
6. For the convenience of temporary DXpeditions, a new JT65 feature
permits use of add-on DXCC prefixes that are not in the published list
of supported prefixes. Both stations in a QSO must enter the required
prefix (for example, PJ8 or FS) in a box on the Setup->Options page.
The effect will be to temporarily add the entry to the table of
7. The Setup->Options page has new entry fields labeled "Source RA"
and "Source DEC". You can enter the current right ascension and
declination of a radio source to be used for system calibration, or
perhaps a pulsar or a deep space probe that you wish to detect. The
program will display (on the Astronomical Data screen) the current
Azimuth and Elevation of the specified object at your station. The
source Azimuth and Elevation are also written every second to the file
azel.dat, in case you have automated tracking capabilities that depend
on this information.
8. For contest-style operations, the Setup->Options menu has an item
labeled "F4 sets Tx6". If this item is checked, when you hit F4 to
clear the To Radio box the program will turn Freeze OFF and set the Tx
message number to 6.
9. To facilitate the coming release of the full source code of WSJT
under the GNU General Public License, the proprietary soft-decision
Reed Solomon decoder has been removed from WSJT proper and made into a
separate executable module, KVASD.EXE. This change is transparent to
the user, and the full benefit of the soft-decision decoder is still
available. An open source hard-decision decoder is also provided; it's
what you get when you select the "Fast" JT65 decoding option.
10. In WSJT 5.8.6, if the value of "Freeze DF" (as displayed in the
Status Bar) differs from the sync tone frequency by more than "Tol",
shorthand decoding was suppressed even if Freeze was not checked. This
is a bug, and it has been fixed.
11. Earlier versions of WSJT had a bug that could cause the "Zap"
function to notch out a valid sync tone. Fixed.
12. The Help screens called up by F1 and Shift-F1 have been updated.
Be sure to read these screens: they contain many operational
conveniences that you may not have discovered!
13. At scrolling speed 5, the time labels and "minute separator" lines
were displayed erratically and the CPU load was excessive. Fixed.
14. Signal strength measurements above -20 dB were formerly compressed
and significantly underestimated. This has been fixed.
15. Decodings of the average of many properly synchronized
transmissions would sometimes go from "good" to "bad" after
approximately 8-12 transmissions. This was a bug, and it has been
16. Several bugs in the FSK441 decoder have been fixed. Both automatic
decoding and mouse-picked decoding have been improved.
17. Changing WSJT modes now sets Auto to OFF, Tol to 400, and the Tx
message number to 1.
18. The generated audio for CW ID in FSK441 and JT6M modes has been
moved to 440 Hz, to avoid possible confusion with the other tones used
in these modes.
19. Readout of "Rx noise" on the main screen is now highlighted in red
if the level is outside the range -10 to +10 dB.
20. The Monitor button is no longer highlighted in green while you are
21. No attempt is made to decode if the Rx level is very low -- for
example, if your receiver is turned off.
22. If the Grid box does not contain a valid locator, readouts of
azimuth and distance are suppressed.
23. Keying of the audio tone to produce Morse code has been softened
to suppress key clicks.
24. Transmitted messages recorded in the file ALL.TXT are now
identified as to mode, and shorthand transmissions are noted as such.
25. A number of other very minor bugs have been fixed.
Changes in WSJT 5.8.6
1. Audio input and output has been modified in a way that accommodates
certain soundcards (e.g., SB Live!) that did not work correctly with
2. New item on Setup->Options menu to select whether GenStdMsgs forces
Tx message number to 1.
3. Status of all selectable items on Setup->Options menu is preserved
on program restart.
4. If a CQ is transmitted in JT65 mode, the Sked box is automatically
5. In v5.8.3, entering the same callsign and locator information in
MyCall and ToRadio/Grid could cause the program to freeze. Fixed.
6. If MyCall includes an extra prefix, as in 4X/ZL1RS, the standard
JT65 messages should not include a grid locator. Fixed.
7. The "ms" parameter has been removed from the Soundcard status
readout at bottom left. Separate sample-rate factors are now
displayed for audio input and output, but only if "Enable diagnostics"
is checked on the Setup menu.
8. The SpecJT screen may now be made invisible by clicking on "X" in
the upper right corner. To restore it to visible status, click
on View->SpecJT on the main screen.
9. Decoded text lines in JT6M mode were sometimes too long, causing
end-of-line wrap-around. Fixed.
10. Some diagnostic messages printed to console window have been
11. The values of S, Sync, Clip, Zap and NB are now preserved when th
program is terminated and restarted.
12. Version 5.8.3 was unable to read back its own recorded wave files.
13. A programming error in the JT65 shorthand message decoder has been
fixed. Under certain conditions, this error could cause false
decodes of shorthand messages.
14. The logic of file saving commands Save Last, Save decoded, etc.,
has been corrected.
15. Wave files read from disk will now produce spectral plots on the
waterfall display if Monitor is OFF.
16. The CW ID feature has been implemented.
17. The mapping of signal levels to pixel colors and its dependence on
settings of Brightness and Contrast controls has been changed so as to
improve sensitivity to very weak signals.
18. In v5.8.3, changing Dsec would create erroneous results for the
displayed soundcard sample rate factor. Fixed.
19. Running in JT65 mode with Dsec>0 caused transmission errors (including
a gap in transmitted tones at t = 38-41 s), and the resulting
transmission was unreadable. Fixed.
20. Undesired resizing of main screen could occur when a long FSK441
message was transmitted. Fixed.
21. The "yellow line" displayed in the graphical area in JT6M mode was
computed incorrectly in version 5.8.3. Fixed.
22. When running at speeds 1-5, the waterfall spectrum may optionally
be "flattened" to remove rolloff at edges. To enable this
feature, check "Flatten spectra" on the SpecJT Options menu.
COMMENTS ON SOUND CARDS
In general, "high end" sound cards offer no advantages when used with
WSJT. Motherboard AC-97 compliant sound systems are cheap and
work well. If you do need to buy a sound card for use with WSJT,
my advice is to get a simple one. You do NOT need 8-channel
surround-sound, wavetable synthesis, special effects, etc. Those
features are for games and listening to music, and they will be wasted
Likewise, you do not need 24-bit A/D and D/A conversions.
Specifications having to do with signal/noise ratio are quite
irrelevant to use with WSJT, as you should never be operating in a
regime where A/D quantizing noise (or any other noise generated in the
sound card) contributes significantly to the system S/N.
If you have a choice, get a card that offers a *native* sampling rate
of 44100 or 11025 Hz, or both. (Unfortunately, it is often very
difficult to tell from the manufacturer's literature whether this
capability is present or not.) If native sampling at 11025 Hz is
available -- or if the manufacturer has at least provided a
well-designed resampling capability -- the soundcard sample-rate
factors (displayed by WSJT in the bottom left corner, if "Setup->Enable
diagnostics" is checked) should both be very close to 1.0000.
Changes in Version 5.8.3
I am aware that some users -- maybe 5 or 10 percent? -- have
been unable to use version 5.8.1 because of erratic audio input levels.
I do not know whether this problem has been solved in 5.8.3, because I
have been unable to reproduce the problem on any computer that I have
access to. It appears to be a problem peculiar to certain sound cards
or Windows configurations.
If you are among those who have experienced the Rx audio problem,
please be sure to read the section headed "KNOWN PROBLEMS", a few
screens down in the above link.
If you experienced the problem but found a solution, please post the
solution to this reflector!
As always, I will be happy to receive your comments on the new release.
Note that I will probably not answer email until some time next week
-- after I have recovered from the ARRL VHF QSO Party, this weekend.
With best wishes,
-- 73, Joe, K1JT
Changes in Version 5.8.1
Beta release 5.8.1 is the first open release of an entirely new
version of WSJT. After a period of beta testing, the program
will become known as WSJT 6.0. I will refer to it here as WSJT6.
Many features of WSJT6 will be familiar to present users of WSJT4.x.
However, the user interface and other real-time portions of the
program have been entirely re-written, so you may find a few things
that look different or work differently than before.
WSJT6 is a multi-threaded program. This architecture permits
much better timing control and much better sharing of the CPU among
the program's many tasks. A real-time waterfall is provided,
optimized for each of the WSJT modes. You can measure and set
the Rx gain in real time. You can decode FSK441 pings
immediately after hearing them.
The decoders for JT65 and JT6M are essentially the same as those in
recent versions of the program. (I have many plans for
enhancements to the decoders, but these must wait for future updates.)
The FSK441 decoder has intentionally reverted back to approximately
version 3.8.1, because it has been shown that recent versions did not
perform quite as well.
WSJT 5.8 is a stable release. Extensive tests by a small group
of early beta testers have already shown that it works well.
However, it contains many thousands of lines of new code, and most
likely that code has some bugs. Nevertheless, I think you will
find many operational advantages to using it. Over the past 2.5
months, all of my own MS and EME QSOs have been made with the new
If you decide to participate in the beta testing period, please accept
the responsibility of reporting any bugs that you find, as well as
telling me of features you would still like to see. I would
appreciate hearing about new features that you like, as well.
PRELIMINARY INSTRUCTIONS AND COMMENTS
1. I suggest installing WSJT6 to a new directory such as C:\Program
Files\WSJT6. After installation you will probably want
your version of the callsign database, CALL3.TXT, into the
WSJT6 directory, replacing the one that is supplied.
2. When you start the program you should get three windows on
screen. One has a black background and I will call it the "console
window"; it is mainly used for debugging messages. You
minimize it and generally ignore it. You should,
there for messages if the program crashes (see also items 9
11, below). The other two windows are a Spectran-like
and the more-or-less familiar WSJT window. It is no
necessary or desirable to run Spectran simultaneously with
3. FSK441, JT65, and JT6M are all present and functional. I have
many QSOs with FSK441 and JT65, so I know they are working
JT6M has been tested somewhat less, but I have seen no
yet. EME Echo mode and the CWID feature are not yet
4. To start the real-time spectral display, click Monitor.
you can leave Monitor on all the time.
5. There are two ways to set the Rx Audio gain. You can
call up the
Windows mixer as before, using the "Rx Volume Control" item
Options menu. There is also a digital gain control near
bottom right of the waterfall screen. You should aim
for around 0
dB, as before -- but with 16-bit audio sampling it is no
very critical. Use the "S-meter" at the lower right of
waterfall display, or the familiar box labeled "Rx noise" at
bottom center of the main screen.
6. You should be able to make FSK441, JT65, and JT6M QSOs more
less as usual. In FSK441 and JT6M you will want to run
spectral display at speed "H1" or "H2" (speed is selected at
top of the waterfall screen). (The "H" means horizontal
scrolling.) Scrolling speeds "5" and "H2" use a lot of
so you may want to avoid them unless your computer is pretty
I generally use speed "1" or "2" for JT65 and "H1" for FSK441
7. When running FSK441 in the horizontal scrolling mode, the
display shows current data in the top half and the previous
sequence in the bottom half. The most recently decoded
is shown also on the main screen, as in version 4.x.
8. You can decode FSK441 pings right away by clicking on any of
2-dimensional spectral displays, or the accompanying green
You can click on the top half, the bottom half, or in the
screen's graphical area.
9. If you have more than one sound card, you can select the
one. Look at the startup messages in the console window.
should see a list of the available Audio devices and
about which one has been selected. If you wish to
selection, enter the desired device numbers on the
screen, then terminate and restart the program.
10. If your display has resolution 1024 x 768 or less, you may prefer
to resize the waterfall window so that only its top portion
remains visible. The two main WSJT windows may then be
visible without overlapping.
11. Some program crashes can kill the console window so that you can't
read the error messages. If this happens, and if the
repeatable, open a Windows Command-Prompt window; CD to your
installation directory, and start the program from there by
"WSJT6". With this startup procedure, any subsequent
will remain visible. Please report any such messages to
12. You may find decoding to be slightly slower than with v4.9.x.
have not yet spent any time optimizing the new code for speed;
will get faster when I turn attention to that task. If
an older computer you may wish to check the menu item
"Setup->Accelerated decoding", which will suspend updating
waterfall during the decoding process.
13. Be sure to look at the screens called up by function keys F1 and
Shift-F1. These screens are also available from the
They list some useful keyboard and mouse commands that you
14. Be sure to explore all the menus and on-screen controls, and try
out the commands listed on the help screens. Until I
time to write a new manual, this is the best way to learn
some of the new features.
15. In JT65 mode, a horizontal green line on the frequency scale shows
the range of frequencies that will be searched for a sync
You can set the "Freeze DF" value by clicking on the main
red curve (as in WSJT 4.x) or by clicking on the waterfall
the shift key held down. If "Freeze" is checked,
ticks will mark the selected sync-tone frequency and the
corresponding frequency of the highest data tone. Red
denote the frequencies of the RO, RRR, and 73 shorthand
16. WSJT6 can read and process WAV files produced by earlier versions.
The converse is not true, however, because earlier versions
WSJT are not equipped to read the 16-bit data files produced
17. When you click "Log QSO," a line with date, time, HisCall,
HisGrid, frequency, and mode is added to the file WSJT.LOG in
18. Every second, a short file named "c:\azel.dat" is updated with
time, moon and sun coordinates, frequency, doppler, and
rate information. This file could be used by other
make your antenna track or your radio follow doppler changes.
19. In the lower left corner of the main screen you will see a message
of the form "Soundcard: x.xxxx", where x.xxxx is a number
1.0000. This number is the ratio of the soundcard's
sampling frequency to the nominal value, 11025 Hz. The
value should stabilize after the program has been running for
minute or so. If you see values less than about 0.9990
than 1.0010, please let me know about it and tell me what
computer and sound card you are using.
20. Callsigns for Swaziland (prefix 3DA0) can now be used in standard
JT65 messages, and they will provide the full "deep search"
21. The box labeled "NB" enables a software noise blanker. If
receiver already has a good noise blanker, this may be of
use; if it does not, you may find this one better than
It can be helpful when short, impulsive noise spikes are
22. The "QRN" parameter of older WSJT versions has been combined with
the "Clip" parameter. In FSK441 mode, Clip=0
corresponds to the
old QRN=5. If you want more FSK441 immunity to
increase Clip above 0 just as you would have increased QRN
23. The "B" and "C" submodes of FSK441 have not been implemented.
far as I could tell, they were little used.
Let me call your attention to the online WSJT Forums hosted by DK5YA
www.vhfdx.de/cgi-bin/yabb/YaBB.pl. If you provide
information and post questions about WSJT 5.8 there, it will help
others as well as yourself -- and may help to reduce the load on my
I do, of course, want to hear from you directly if you have found a
problem with the new program version or suggestions for its
With best wishes,
-- 73, Joe, K1JT
Changes in Version 4.9.8
Version 4.9.8 is a minor maintenance release. The changes are:
1. Bug in JT65 decoder could (rarely) cause a correct decoding by the
Reed-Solomon decoder to be "overruled" by an incorrect decoding
from the Deep Search decoder. Fixed.
2. Bug in JT65 Reed-Solomon decoder could cause program to crash under
certain rare conditions. Fixed.
3. The standard "CQ" message generated for a callsign having an extra
prefix or suffix should not include a grid locator. Fixed.
4. Automatically generated CW messages for stations with callsigns longer
than 4 characters were improperly truncated. Fixed.
5. Bug in JT65 decoder could occasionally cause one or two extra
letters to be appended to a correctly decoded callsign. Fixed.
6. Grid locator entered in "Report" box in FSK441 mode (as used by
some in North American meteor scatter contest) would cause a crash
on program restart. Fixed.
Changes in Version 4.9.7
The latest update is WSJT Version 4.9.7. Like Version 4.7.0, it
is able to run simultaneously with the latest version of Spectran (by
I2PHD and IK2CZL), which is included with the 4.7.0 distribution. This
combination of programs provides an excellent real-time spectral display
in addition to all the features of WSJT.
Changes in Version 4.9.6
1. WSJT 4.9.5 fails to decode some files that have relatively
high S/N and good Sync level. This is a bug, and has been fixed. For
this reason alone, you should definitely upgrade to Version 4.9.6.
2. New optional message formats are provided for conveying and
responding to signal reports. It has been permissible for some time to
send, for example,
VK7MO K1JT -24
K1JT VK7MO R-27
(The number after the minus sign must have two digits and must be in the
range -01 to -30.)
I plan to implement a quick way of copying the measured strength of a
decoded transmission into TX message #2, when desired. This is not yet
done in v4.9.6, however. You must edit the TX messages by hand if you
use these formats.
Enhancements in version 4.9.6 now allow you to send messages like the
ones listed below. Both stations will need to be running v4.9.6 in order
for these to work:
VK7MO K1JT RO
VK7MO K1JT RRR
VK7MO K1JT 73
3. Decoding by the deep search algorithm has been extended so as to
include messages of the types discussed in item 2.
Changes in Version 4.9.5
1. Full support for long callsigns like ZA/PA2CHR and G4ABC/P is
now provided. When using such a callsign prefix or suffix, do not
include a grid locator in your transmitted message.
2. If you double-click on a callsign in the decoded text window, and if
the word preceding the callsign is "CQ", then TX message #1 will be
selected after the messages are updated. Otherwise, TX message #2 will
3. So that you will be aware of what is happening, the background color
in the TX message box turns red whenever a message you have entered is
"non-standard" and will be sent as 13 characters of plain text.
4. Items related to decoding have been removed from the Setup |Options
screen and replaced by a new menu labeled Decoding. Here you may now
select "No shorthands" for FSK441 and several options for JT65 decoding.
5. In case you are upgrading directly from WSJT v4.7.0 to v4.9.5, a
callsign database file has been included as CALL3A.TXT. If you do not
already have a file CALL3.TXT, you should rename the supplied file to
CALL3.TXT. Otherwise, you will probably want to ignore the supplied
file, since you will have made additions to your own copy.
6. The frequency of program crashes (for example, after a long period of
monitoring) is much reduced, possibly to zero.
Please, if you encounter a received wave file that reproducibly cause
WSJT to crash, send it to me.
Changes in Version 4.9.2
1. In CW mode you can now set the desired T/R period by using the
text box provided. This feature did not work properly in v4.9.1.
2. Under some conditions using the "Add" button to edit information in
the file CALL3.TXT would cause a program crash with the message
"Run-time Error #53". Fixed.
3. Using the double-mouse-click on a callsign in the decoded text window
will now set the active Tx Message to Tx2. I believe this will be most
commonly what is desired, and will be an added convenience for random
4. The "Sked" box remained visible on the EME Echo screen, covering part
of the RIT box. Fixed.
5. Two numbers are now made available if you have checked the"Aggressive
decoding" option. These numbers appeared without explanation at the end
of each decoded text line produced by version 4.9.1, and you may have
wondered what they were. The first number is 0 or 1 according to whether
the soft-decision Reed Solomon decoder has failed or succeeded. The
second number represents a confidence level on a 0-10 scale for messages
decoded using the "deep search" algorithm. Anything under 3 is
questionable; messages rated 6 and above are unlikely to be wrong,
unless you are processing "garbage" data containing strong birdies, QRN,
etc. In that case, you are on your own.
6. A bug was introduced when implementing the "Aggressive decoding"
check box. This bug caused a stray "OOO" flag to be sometimes displayed
even when no signal was present and synchronization had not been
Changes in Version 4.9.1
1. A programming error in version 4.9.0 prevented the "deep search"
portion of the JT65 decoder from detecting some messages that include
the "OOO" signal report. The bug has been fixed, and consequently the
extra 4 dB of sensitivity will become available for those messages.
2. The callsign database, a file named CALL2.TXT in version 4.9.0, has
been converted to a comma-delimited format and is now named CALL3.TXT.
As has been true in the past, you should maintain your own copy of this
file according to your own needs. New calls may be added to the file
using the "Add" button of WSJT, and you can edit the file directly with
the Windows NotePad program. I apologize for the fact that if you have
already edited CALL2.TXT extensively, you will need to do so again. The
good news is that the programs WSJT, MoonSked (by GM4JJJ) and Tracker
(by W7GJ) will now use the same database file, CALL3.TXT.
3. Two new JT65 check boxes have been made available to the user: one
labeled "Sked", located on the main screen, and one labeled Agressive
decoding" on the Setup | Options screen. Check "Sked" to signify that
you are trying to work a known station; the deep search decoder will
then look only for your own call and the one displayed in the "To Radio"
box. Check "Agressive search" if you want to see all messages found by
the deep-search decoder, even if the confidence level is moderately low.
Leave this box unchecked if you prefer to see only decoded messages that
have been assigned a relatively high confidence.
4. The duration of T/R sequences in CW mode defaults to 60 s if the Band
is 50 MHz, 150 s if 432 MHz, and 120 s otherwise. However, an on-screen
box now allows you to override the defaults and set any
Changes in Version 4.9.0
On the outside WSJT version 4.9.0 looks nearly the same as its
recent predecessors. A "CW" entry now appears on the Mode menu. This is
presently a "transmit only" mode: it sends standard EME-style messages
at 15 WPM, by keying a 1500 Hz audio tone, and it takes care of the
timing and T/R switching for you. Receiving is left up to you, the
operator. For me, this combination makes CW EME QSOs relaxing and
enjoyable. Presently the program uses 2.5 minute sequences if you are on
432 MHz, 2 minutes on 144 MHz, and 1 minute on 50 MHz. (If you want to
run with 1-minute sequences on 144, set the band indicator to 50 MHz.)
Double-clicking on a callsign in either one of the decoded text windows
will cause that callsign to be copied into the "To Radio" box. The call
will then be looked up in the database and will be inserted
appropriately into the transmit message boxes Tx1 and Tx2. This feature
is designed to facilitate random JT65 operation by making it easy to
call a station you have just copied calling CQ, or responding to your CQ.
The most significant program enhancements are those made to the JT65
decoder. It has been transformed into a multi-layered procedure that
takes better advantage of the structured nature of JT65 messages and the
substantial computing capability that most WSJT users have in their
In version 4.9.0, if the initial JT65 decoding effort fails then deeper
searches are attempted using an entirely different approach. The result
is a net gain of about 4 dB over a wide range of circumstances. My JT65
digital simulator, which has accurately predicted the performance of
previous versions of the software, correctly decodes about 50% of
simulated Rx files with the v4.7.0 decoder at a signal level of -24 dB.
With the v4.9.0 decoder, it correctly decodes more than half of the
simulated data files at -28 dB. This very substantial improvement means
that JT65's message-averaging facility will be needed much less
frequently than with earlier versions of WSJT. Most of the time, if the
transmission synchronizes properly, it will also decode properly.
You will get better performance from the new JT65 decoder if you
understand a few things about how it works. The following is a very
brief description; more complete technical details will be forthcoming
then I find time to write it all down.
JT65 is capable of transmitting and receiving 2^72 (about 5 x 10^21)
distinct user messages. Instead of sending the minimum number of 72
information bits needed to to convey any one of those distinct messages,
the program actually sends 63 six-bit "symbols" for a total of 378 bits
in each transmission. The 302 extra bits comprise the powerful forward
error correction (FEC) capability of the JT65 mode, allowing the system
to function reliably with signals far below the audible threshold.
One of the first tasks of the JT65 decoder is to measure the signal
level at each of the 64 data-tone frequencies during each of the 63 data
intervals in a transmission. The program must then decide which one of
the possible 2^72 messages was most likely the one sent. The procedure
is necessarily probabilistic in nature. The best decoder will go as far
down into the noise as possible, but it must also know when to give up
so that it produces few false decodes.
The total of 2^72 distinct messages is far too many to permit each one
to be tested individually against the received signal. However, an
important characteristic of the Reed-Solomon FEC code used in JT65 is
that well-defined mathematical algorithms can be used to direct the
decoder toward the most likely candidate messages, based on the
available signal information. A mathematical inversion of the code is
made possible by the organization of the redundant information contained
in the 306 extra bits.
The new JT65 decoder goes far beyond the capabilities of normal
Reed-Solomon decoders. If the standard decoding procedure fails to
produce a high-confidence solution, the program proceeds to search
explicitly for each one of a number of messages that it considers likely
or plausible on other grounds.
Nearly 2^28 (over 250 million) different callsigns can be accommodated
in each of the two callsign fields of a JT65 message. Once again,
this is far too many to permit an exhaustive search for them all.
Consequently, the "deep search decoder" takes the callsigns listed in
the file CALL2.TXT (located in the user's WSJT directory) as being the
most likely alternatives in the message's second field. A correlation
algorithm is then applied to find out if one of these calls and its
associated grid locator are present, combined with either "CQ" or the
receiving station's callsign in the first field. High-confidence
matching of this kind can be accomplished down to about -28 dB on the
WSJT scale, in a single transmission, with a very low error rate.
The bottom line is that for any arbitrary callsign the new JT65 decoder
performs at least as well as the one in WSJT version 4.7.0. Message
averaging works just as it did before, and if you are listening in to a
"third party" QSO between two other stations, the sensitivity will be
the same as in version 4.7.0. However, if a station that is listed in
the file CALL2.TXT is calling CQ or is calling you, your sensitivity
will be about 4 dB better on average.
Please note that the decoder is given no information whatsoever about
what station you may be trying to work. Its heart is "as pure as the
driven snow," even if you are working a sked. However, the decoder does
make the educated guess that the callsign of the transmitting station is
more likely to be one listed in CALL2.TXT than some other callsign
constructed at random.
The program always attempts to decode a purely arbitrary message first.
Failing that, it will look more deeply in the noise for the presence of
a message that includes the callsign of a station listed in the database
It is no accident that the algorithm just described bears close
resemblance to the thought processes (conscious and otherwise) that we
use to copy very weak CW by ear. Familiar combinations like CQ and one's
own callsign are always easier to dig out of the noise than random
combinations of characters. Callsigns that we have seen or heard before
are more easily recognized than arbitrary calls generated at random. The
new JT65 decoder behaves similarly, except that it is kept fully in the
dark about who you are trying to work.
A final note: the file CALL2.TXT replaces the file CALLSIGN.TXT used by
earlier versions of WSJT. The format has been changed to permit extended
callsigns such as those sometimes used by DXpeditions, for example
ZA/PA2CHR. The name of the database file has been changed so as not to "break"
an earlier version of WSJT that you may wish to keep available. Full
support for extended callsigns (i.e., calls with an extra prefix or
suffix) is planned for a future version of WSJT.
Changes in Version 4.7
4.7.0 Includes version 2.0 (build 213) of Spectran, by I2PHD and IK2CZL.
WSJT and Spectran can run simultaneously.
If you have already installed WSJT, you can upgrade to the current
version by downloading and executing UPD470.EXE.
Versions 4.0 and later will not overwrite an installed version of WSJT
3.x. You may, for example, have versions 3.8.1 and 4.6.1 installed at
the same time, which will give you access to JT44 as well as the newer
JT6M, JT65, and FSK441 modes.