diff --git a/doc/user_guide/en/images/FST4-1.png b/doc/user_guide/en/images/FST4-1.png new file mode 100644 index 000000000..bfe1e5d20 Binary files /dev/null and b/doc/user_guide/en/images/FST4-1.png differ diff --git a/doc/user_guide/en/images/FST4-2.png b/doc/user_guide/en/images/FST4-2.png new file mode 100644 index 000000000..d173bd96f Binary files /dev/null and b/doc/user_guide/en/images/FST4-2.png differ diff --git a/doc/user_guide/en/images/FST4W-1.png b/doc/user_guide/en/images/FST4W-1.png new file mode 100644 index 000000000..85eb3c7d9 Binary files /dev/null and b/doc/user_guide/en/images/FST4W-1.png differ diff --git a/doc/user_guide/en/images/FST4W-2.png b/doc/user_guide/en/images/FST4W-2.png new file mode 100644 index 000000000..22ed3d14b Binary files /dev/null and b/doc/user_guide/en/images/FST4W-2.png differ diff --git a/doc/user_guide/en/tutorial-example5.adoc b/doc/user_guide/en/tutorial-example5.adoc index d827c0a19..8cc08b539 100644 --- a/doc/user_guide/en/tutorial-example5.adoc +++ b/doc/user_guide/en/tutorial-example5.adoc @@ -1,5 +1,17 @@ Do not confuse FST4 with FT4, which has a very different purpose! -FST4 is designed primarily for making 2-way QSOs on the LF and MF bands. +FST4 is designed primarily for making weak-signal 2-way QSOs on the +LF and MF bands. T/R periods from 15s up to 1800s are +available. Longer T/R periods provide better sensitivity provided that the +combined effects of Tx and Rx frequency instability and channel Doppler spread +yield a received signal that remains coherent over the duration of +several transmitted symbols. Generally speaking, Rx and Tx frequency changes +during the transmission and channel Doppler spread should each be small compared +to the symbol keying rate shown for each T/R duration in Table 7 within section +<>. For example, the keying rate for the 1800s T/R period is 0.089 Baud, so +successful operation using this T/R length requires Tx and Rx frequency +stability better than 0.089 Hz over the duration of the 1800s transmission in +addition to channel Doppler spread smaller than 0.089 Hz. + Operation with FST4 is similar to that with other _WSJT-X_ modes: most on-screen controls, auto-sequencing, and other features behave in familiar ways. However, operating conventions on the 2200 and 630 m @@ -21,3 +33,12 @@ decoding process (and of course will be undecodable). By checking further limit the decoding range to the setting of *F Tol* on either side of *Rx Freq*. +.Open a Wave File: + +- Select *FST4* on the *Mode* menu. Set *T/R* to 60 s and *Decode | Deep*. +- Set *F Low* 1000, *F High* 1400. +- Open a sample Wave file using *File | Open* and select the file +...\save\samples\FST4+FST4W\210115_0058.wav. When the file opens you should see something similar to the following screen shots: + +image::FST4-1.png[align="left"] +image::FST4-2.png[align="left"] diff --git a/doc/user_guide/en/tutorial-example6.adoc b/doc/user_guide/en/tutorial-example6.adoc index 4fe4804e3..d8df2e992 100644 --- a/doc/user_guide/en/tutorial-example6.adoc +++ b/doc/user_guide/en/tutorial-example6.adoc @@ -1,5 +1,5 @@ FST4W is used in the same way as WSPR, but FST4W has significant -advantages for use on the 2200 and 630 m bands. By default the +advantages for use on the 2200 m and 630 m bands. By default the central *Rx Freq* is 1500 Hz and *F Tol* is 100 Hz, so the active decoding range is 1400 to 1600 Hz. However, for added flexibility you can select different center frequencies and *F Tol* values. We expect @@ -16,3 +16,27 @@ If three operators agree in advance to select the options *1/3*, a fixed sequence with no two stations transmitting simultaneously. Sequence 1 is the first sequence after 00:00 UTC. For WSPR-like scheduling behavior, you should select *Random* with this control. + +.Open a Wave File: + +- Select *FST4W* on the *Mode* menu. Set *T/R* to 1800 s and *Decode | Deep*. +- Select appropriate wide graph settings. For example, try *Bins/Pixel* 1, +*Start* 1200 Hz and *N Avg* 150. +- Enable the multi-threshold noise blanker by setting the noise blanker *NB* to -1. +This setting tells the decoder to try 0, 5, 10, 15, and 20 % blanking. +The *NB* setting is located just above the green receive power indicator and below the +frequency selection menu. +- Open a sample Wave file using *File | Open* and select the file +...\save\samples\FST4+FST4W\210203_0600.wav. Processing may take a minute or +more because of the noise blanker setting. When it is finished you should +see a single decode as shown in the screenshot: + +image::FST4W-1.png[align="left"] +image::FST4W-2.png[align="left"] + +The weak signal associated with the single decode is all but invisible on the +widegraph spectrogram. Note that the sample wave file will not decode if +the noise blanker is turned off +(*NB* set to 0 %) or if it is set to any positive number less than 14 %. Using +*NB* -1 tells WSJT-X to try noise blanker settings 0, 5, 10, 15, and 20 %. Similarly, +*NB* -2 tells WSJT-X to try noise blanker settings 0, 2, 4, 6, ..., 20 %.