6 Commands
58
BPM exhibits a 0/0 bandwidth of only 20Hz, which with conventional methods requires
extremely exact and stable tuning for good results).
The Auto-Correlation method is also the basis of the AGC used in the CW demodulator,
with a dynamic range of approximately 40 dB. The AGC allows a constantly good
receive performance, independent of audio input signal level.
The Audio frequency of the CW terminal is defined by the
Center
command of the
aud:-
menu, independently of the actual Mark frequency (refer to chapter
, page
The CW terminal offers the use of a number of so-called hot-keys:
BREAKIN-Character (Ctrl-Y):
When pressed twice, the BREAKIN character leads to
switching between direct transmission of the keyboard input (Immediate transmission
mode), and a delayed switch over (Delayed transmission mode).
This delayed switching allows text to be "typed ahead" whilst reading the other QSO
partners transmission. The text in the buffer can then be transmitted by pressing the
BREAKIN-character (<Ctrl-Y>) once. The transmission is then only blocked again
when no characters are transmitted for 6 seconds. This has the advantage that user may
continue writing after the buffered text is sent, without having to press any other key.
The renewed blocking of the transmitted is shown by the PTC-IIIusb with the message
'>>>' written to the Delayed Echo-window.
After switching to the CW-Terminal, one is always in the direct transmission mode.
Ctrl-U and Ctrl-D:
Increases (Up) or decreases (Down) the decoder speed by 1/16 the
actual value. This is mainly for use when the automatic RX speed adjustment is turned
off.
Ctrl-F:
Switches between automatic and manual RX speed adjustment (fixed speed
mode). On switching between the two possibilities, the present speed is taken without
change, so that in practice, one can leave the automatic adjustment running for a while
to set the correct speed, then press <Ctrl-F> to keep this setting. The operation with a
fixed speed has definite advantages with weak signals, or signals with heavy fading.
The decoder withstands speed errors of 40 percent without problem, so that even with
a fixed speed setting, virtually no reading errors are found.
After switching on the CW-Terminal, it is always switched to the automatic speed
adjustment mode.
The PTC's automatic CW decoder can operate with speeds between 30 and
approximately 300 letters per minute, and scans this range within 10 seconds.
It decodes all letters from
a-z
all numbers from
0-9
special characters
, . : ? / - = SK# EB> AR* KN( VE+ KA!
German Umlauts
ä, ö, ü or ch
All ambiguous signals are ignored.
Naturally, an automatic decoder can only decode relatively well sent Morse code signals.
One hears unfortunately much badly sent Morse on the bands (not only amateur signals!!)
where commonly the Mark/Space ratio is incorrect. One must then bear in mind that not
all CW QSO's will be correctly decoded.
The CW terminal can be closed with the
D
command, or
DD
may also be used.