Microlog SWL, Manual, Page: 24 / 36

Experimenting in this fashion with hand sent code will assist you
in becoming familiar with the MORSE decoding algorithm. You can
also listen to your code by turning up the volume on your video
monitor’s audio channel. This feature will also be very useful in learn­
ing to send Morse code should you desire to get an amateur radio
license.
Now enable the SPEED-LOCK feature by typing ‘CTRL T’. You
should still be able to speed up or slow down within the ± 50 % range
and properly display the decoded characters, however the speed
display on the top line will no longer be updated. You may still
calibrate the system to your fist by pressing ‘CTRL X’, then the speed.
Note that when the SPEED-LOCK is enabled, the word ‘LOCK’ ap­
pears in the status block on the top video line.
Remember that the speed displayed on the top line simply
represents the system’s internal value of the average dot + element
space. For example, consider the case of the perfect code at 20 WPM.
Both dot and element space will be equal in length, the actual dot
length will be .06 seconds. This is based on the formula,
(speed in WPM) X (dot length in seconds) = 1.2
Thus, when the top line displays a MORSE speed of 20 WPM it
means that the system’s current value for the so called “average dot” is
60 milliseconds. All incoming code elements (dots, spaces, dashes) are
then compared against this current “average dot” value as part of the
decoding algorithm’s decision process as previously described. This
“average dot” is continuously being updated based on the incoming
code elements, and the speed display gets updated periodically.
5.2 RECEIVING:
You should now be ready to copy MORSE signals from your
receiver. Entering this mode will automatically enable the single chan­
nel detector. To verify simply observe the topline display. The cross
hatch is inhibited and the red dot is used as the tuning indicator. Note
that “NOR/INV” does not function in MORSE.
Disconnect the hand key input, and reconnect the audio from your
receiver to the rear panel of the SWL. Tune the receiver to a MORSE
signal, and place your receiver’s AGC in the fast position. The “WIDE-
NARROW” switch should be in the “NARROW” position resulting in
an effective CW copying bandwidth of about 200 to 300HZ.
As you tune the signal across your receiver’s pass band you should
be able to hear a regenerated signal if you turn up the audio volume on
your video monitor (or television). In the single tone mode the system is
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