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43 lines
2.1 KiB
Plaintext
43 lines
2.1 KiB
Plaintext
FST4W is used in the same way as WSPR, but FST4W has significant
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advantages for use on the 2200 m and 630 m bands. By default the
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central *Rx Freq* is 1500 Hz and *F Tol* is 100 Hz, so the active
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decoding range is 1400 to 1600 Hz. However, for added flexibility you
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can select different center frequencies and *F Tol* values. We expect
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that usage conventions will soon be established for FST4W activity on
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2200 and 630 m.
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A new drop-down control below *F Tol* offers a round-robin mode for
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scheduling FST4W transmissions:
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image::FST4W_RoundRobin.png[align="center"]
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If three operators agree in advance to select the options *1/3*,
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*2/3*, and *3/3*, for example, their FST4W transmissions will occur in
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a fixed sequence with no two stations transmitting simultaneously.
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Sequence 1 is the first sequence after 00:00 UTC. For WSPR-like
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scheduling behavior, you should select *Random* with this control.
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.Open a Wave File:
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- Select *FST4W* on the *Mode* menu. Set *T/R* to 1800 s and *Decode | Deep*.
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- Select appropriate wide graph settings. For example, try *Bins/Pixel* 1,
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*Start* 1200 Hz and *N Avg* 150.
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- Enable the multi-threshold noise blanker by setting the noise blanker *NB* to -1.
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This setting tells the decoder to try 0, 5, 10, 15, and 20 % blanking.
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The *NB* setting is located just above the green receive power indicator and below the
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frequency selection menu.
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- Open a sample Wave file using *File | Open* and select the file
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...\save\samples\FST4+FST4W\210203_0600.wav. Processing may take a minute or
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more because of the noise blanker setting. When it is finished you should
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see a single decode as shown in the screenshot:
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image::FST4W-1.png[align="left"]
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image::FST4W-2.png[align="left"]
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The weak signal associated with the single decode is all but invisible on the
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widegraph spectrogram. Note that the sample wave file will not decode if
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the noise blanker is turned off
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(*NB* set to 0 %) or if it is set to any positive number less than 14 %. Using
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*NB* -1 tells WSJT-X to try noise blanker settings 0, 5, 10, 15, and 20 %. Similarly,
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*NB* -2 tells WSJT-X to try noise blanker settings 0, 2, 4, 6, ..., 20 %.
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