WSJT-X/README.TXT
Joe Taylor 2c17544f3f initial import
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/WSJT/trunk@1 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2005-12-22 16:40:53 +00:00

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Changes in WSJT 5.9.0 -- November 15, 2005
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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) will set "Freeze DF" at the selected
frequency, turn Freeze ON, and invoke 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 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
correct. In addition, your digitized Rx signals will be adjusted
so that the software can properly interpret them.
This 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 screen.
5. 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
approximately equally 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 supported prefixes.
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. To facilitate the coming release of the full source code of WSJT
under the General Public License, the proprietary soft-decision
Reed Solomon decoder has been removed from WSJT proper and made
into a separate executable module. This change is invisible 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.
9. 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.
10. Earlier versions of WSJT also had a bug that could cause the "Zap"
function to notch out a valid sync tone. Fixed.
11. 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!
12. At scrolling speed 5, the time labels and "minute separator" lines
were displayed erratically and the CPU load was excessive. Fixed.
13. Signal strength measurements above -20 dB were formerly compressed
and significantly underestimated. This has been fixed.
14. 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 fixed.
15. Several bugs in the FSK441 decoder have been fixed. Both automatic
decoding and mouse-picked decoding have been improved.
16. Changing WSJT modes now sets Auto to OFF, Tol to 400, and the Tx
message number to 1.
17. The generated audio tones for CW ID in FSK441 and JT6M modes have
been moved down to 440 Hz, to avoid possible confusion with the
other tones used in these modes.
18. Readout of "Rx noise" on the main screen is now highlighted in red
if the level is outside the range -10 to +10 dB.
19. The Monitor button is no longer highlighted in green while you are
transmitting.
20. No attempt is made to decode if the Rx level is very low -- for
example, if your receiver is turned off.
21. If the Grid box does not contain a valid locator, readouts of
azimuth and distance are suppressed.
22. Keying of the audio tone to produce Morse code has been "softened"
to suppress key clicks.
23. Your transmitted messages recorded in the file ALL.TXT are now
identified as to mode, and shorthand transmissions are noted.
23. A number of other very minor bugs have been fixed.