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Example Files
To gain some familiarity with the operation of WSJT, use the program to decode some
example files provided with the standard installation. Hit function key F7 to choose
FSK441A mode, and select Open from the File menu. Navigate to the
RxWav\Samples
folder in your WSJT home directory and open the file recorded from W8WN. When this
file has been decoded, the top of your screen should look like the picture on page 2. With a
speaker or headphones connected to the soundcard output, listen to the recording by clicking
the Play button. You will hear static crashes at the beginning of the file and a moderately
strong ping from W8WN about 18 seconds later. Try clicking around the ping with both left
and right mouse buttons, and observe the decoded text that appears. Click the Big
Spectrum button to see what these signals look like on the large waterfall display. Click
Erase on the main screen to clear the text and graphical areas.
Next, select JT6M from the Mode menu and open the sample file from AF4O. Nothing
decodes automatically in this file—the signal is very weak—but try right-clicking on the
green line at about t = 12.9 s, as displayed on the green label at lower left of the plot area.
You will find that AF4O was calling K1JT. Try listening to this file: the signal is audible
some of the time, but only barely. Finally, switch to JT65A mode and open the recording
from OH7PI. The graphics window and decoded text boxes on your screen should look like
the picture on page 5. Listening to this file, you will hear only random noise. OH7PI’s 144
MHz EME signal was much too weak for CW communication at this time, but he was solid
copy in JT65.
Adjusting Signal Levels
1. Turn on your radio and tune it to a clear frequency so that only background noise is sent
to the sound card.
2. Press F9 to select the EME Echo mode.
3. Select Setup | Adjust RX Volume control to bring up the sound card input mixer.
4. Click Measure to start a sequence of noise measurements
5. Adjust a slider on the audio mixer and/or your receiver gain control(s) so as to bring the
signal level close to what WSJT calls “0 dB”. The signal level is displayed numerically
and illustrated by a green line in the plot area. The green curve should be approximately
aligned with tick marks on the left and right border.
6. Press F7 to enter FSK441A mode.
7. Click Record to start a receiving period. The program will record noise for 30 seconds
and then attempt to decode it. This should produce a jagged green line in the large plot
area, along with a waterfall-style spectrogram. The green line is a graph of received
noise power vs. time. The waterfall is a time vs. frequency spectrogram in which
frequency increases upward, time to the right.
8. Select Setup | Adjust TX Volume control to bring up the sound card output mixer.
9. Turn off your final amplifier (if any). Click one of the four Tune buttons A, B, C, or D
to be sure that T/R switching works and an audio tone is sent from the computer to your
radio.
10. Adjust the slider on the audio mixer to get the proper audio signal level for your
transmitter. Watch the transmitter power output while sending each of the four tones A,
B, C, and D. Variations of 10% or even 20% among the four tones are acceptable, but
50% differences will degrade your signal. You may find it useful to experiment with the
setting of a speech processor or ALC control.
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