SCS PTC-IIex, Manual

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6 Commands
6.89 SPAce
Default setting: 1200
Parameter: X 300... 2700, frequency in Hz.
Allows the adjustment of the space frequency of the PTC-IIex in 1 Hertz steps (internal
resolution 0.25 Hz, using DDS). The frequency chosen is only used when the
TOnes
parameter is set to 2. (refer to chapter 6.96 , page 82 ).
6.90 SQuelch
Default setting: 45
Parameter: X 0… 99, Value for the noise suppression.
100… 200, used for ZCZC/NNNN autostart
The trigger point for the software squelch (noise suppression) for Baudot RTTY can be
set using the
SQuelch
command, with values between 0 to 99. With the value 0, the
squelch is always open (noise-suppression turned off). With the value 99 the squelch is
always closed (all signals suppressed). With a value of about 40, the squelch remains
closed on a totally free channel, but is very sensitive to changes in the signal spectrum on
that channel. Even very weak and noisy RTTY signals should correctly open the squelch,
when it is set to the standard value of 45. An open squelch is displayed on the PTC front
panel by either the Idle or Traffic LED lighting (depending on the received RTTY signal).
Coastal radio stations or other professional RTTY stations normally send the character
string ZCZC in advance to a new message. The end of a message is followed by the
character string NNNN.
This can be used to make a Start/Stop squelch available. If ZCZC/NNNN is activated the
PTC-IIex receive in the Baudot/RTTY mode only if the pattern ZCZC is found in the data
stream. As commercial radio stations only send for a short time at a day, using this special
(digital) squelch can reduce the accidental
received QRM drastically.
The ZCZC/NNNN autostart can be activated setting the squelch parameter to a value
between 100 and 200. If the squelch value is set to 140, the PTC-IIex operates with the
ZCZC/NNNN autostart and additionally with the normal analog squelch of 40 (value
minus 100). This means that also during open autostart squelch the receiption is
interrupted, if the signal falls below a certain level.
6.91 STatus
Default setting: 1
Parameter: 0 Status checking on (see text).
1 Status checking on.
2 Status checking on (automatic status output).
The status word polling in the PTC-IIex is permanently turned on. The parameter 0 has
only been retained for compatibility reasons.
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