diff --git a/doc/user_guide/en/tutorial-example5.adoc b/doc/user_guide/en/tutorial-example5.adoc index b248dd002..db4e81f66 100644 --- a/doc/user_guide/en/tutorial-example5.adoc +++ b/doc/user_guide/en/tutorial-example5.adoc @@ -1,15 +1,17 @@ Do not confuse FST4 with FT4, which has a very different purpose! 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 +LF and MF bands. T/R periods from 15 s up to 1800 s are +available. Longer T/R periods provide better sensitivity only if +Tx and Rx frequency instability and channel Doppler spread +are small enough so that received signals +remain phase coherent over periods spanning 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 +<>. For example, the keying rate for +the 1800 s 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 +stability better than 0.089 Hz over the duration of the 1800 s 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 @@ -33,15 +35,26 @@ 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: +A noise blanker can be enabled by setting the *NB* percentage to a non-zero value. +This setting determines how many of the largest-amplitude samples will be +blanked (zeroed) before the data is submitted to the decoder. Most users find +that settings between 0% (no blanking) and 10% work best. If the noise +blanker percentage is set to -1%, then the decoder will try 0, 5, 10, 15, and 20 % +in succession. Similarly, a setting of -2% causes the decoder to loop over +blanking percentages 0, 2, 4, ... 20 %. To save time, the multiple blanking +percentages triggered by negative *NB* settings are tried only for signal +candidates located near (within +/- 20 Hz) of the *Rx* frequency setting. + +.Open a sample Wave File: - Select *FST4* on the *Mode* menu. Set *T/R* to 60 s and *Decode | Deep*. -- Set up the Wide Graph display so that it has settings appropriate for the FST4-60 mode. +- Set *NB* (noise blanker) to 0%. +- Set up the Wide Graph display with settings appropriate for the FST4-60 mode. For example, try *Bins/Pixel* 2 and *N Avg* 4. Set the *Start* frequency and the width of -the Wide Graph to cover the entire frequency range that you want to decode. For this +the Wide Graph to include the frequency range that you want to decode. For this example, make sure that *Start* is less than 1000 Hz and that the Wide Graph extends to above 1400 Hz. - Set *F Low* 1000, *F High* 1400. These settings define the decoder's frequency search range. - 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 shot: +...\save\samples\FST4+FST4W\210115_0058.wav. After _WSJT-X_ has processed the file you should see something similar to the following screen shot: image::FST4-1.png[align="left"] diff --git a/doc/user_guide/en/tutorial-example6.adoc b/doc/user_guide/en/tutorial-example6.adoc index 3c5c621ee..88838b5d5 100644 --- a/doc/user_guide/en/tutorial-example6.adoc +++ b/doc/user_guide/en/tutorial-example6.adoc @@ -20,6 +20,7 @@ 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*. +- Set *NB* to 0%. - Select appropriate wide graph settings. For example, try *Bins/Pixel* 1, *Start* 1200 Hz and *N Avg* 150. - Open a sample Wave file using *File | Open* and select the file