Re-do the FST4W-1800 example.

doc/user_guide/en/tutorial-example6.adoc

@@ -22,21 +22,12 @@ scheduling behavior, you should select *Random* with this control.
 - 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
+...\save\samples\FST4+FST4W\201230_0300.wav. 
-more because of the noise blanker setting. When it is finished you should 
+When it is finished you should see a single decode as shown in the 
-see a single decode as shown in the screenshot:
+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 
+Note that 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 
+widegraph spectrogram. 
-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 %.