E F Johnson Company 2425770 Benutzerhandbuch
5-4
Viking Portable 600 Radio Operating Manual
Conventional Mode Features
The Call Guard squelch feature eliminates distracting messages intended for others using
the channel. This is done by using a subaudible tone or digital code to control the squelch.
This tone or code is unique to a user or a group on that channel. This tone or code is
transmitted with the voice signal but is not heard because it is in the subaudible range and
is attenuated by a filter. Call Guard squelch must be used in both the transmitting and
receiving radio to be functional.
the channel. This is done by using a subaudible tone or digital code to control the squelch.
This tone or code is unique to a user or a group on that channel. This tone or code is
transmitted with the voice signal but is not heard because it is in the subaudible range and
is attenuated by a filter. Call Guard squelch must be used in both the transmitting and
receiving radio to be functional.
5.4.1 Call Guard Squelch Enable / Disable
The Normal/Selective option button (if programmed) or menu parameter can be used to
disable receive Call Guard squelch on analog channels or talkgroup ID code detection on
P25 channels. When selective squelch is disabled, “Sq Normal” is flashed in the display,
and when it is enabled, “Sq Select” is flashed.
disable receive Call Guard squelch on analog channels or talkgroup ID code detection on
P25 channels. When selective squelch is disabled, “Sq Normal” is flashed in the display,
and when it is enabled, “Sq Select” is flashed.
When “Normal” is selected, the receiver unsquelches only if a carrier is detected.
Scanning and Project 25 NAC detection are not disabled with this mode selected. The
selected mode is in effect until it is manually changed again. Selecting another channel or
cycling power does not reselect a default condition. There is a programmable option to
display the monitor icon when the “Normal” mode is selected.
Scanning and Project 25 NAC detection are not disabled with this mode selected. The
selected mode is in effect until it is manually changed again. Selecting another channel or
cycling power does not reselect a default condition. There is a programmable option to
display the monitor icon when the “Normal” mode is selected.
5.4.2 Tone Call Guard Squelch
Tone-type Call Guard squelch uses subaudible CTCSS tones from 67-254.1 Hz. Although
there are 42 tones assigned, those above 33 (210.7 Hz) are normally not used because of
their close proximity to the voice band which starts at 300 Hz. In addition, tones 11 (97.4
Hz), 39 (69.3 Hz), 40 (206.5 Hz), 41 229.1 Hz), and 42 (254.1 Hz) are normally not used
because they may cause interference with adjacent tones.
there are 42 tones assigned, those above 33 (210.7 Hz) are normally not used because of
their close proximity to the voice band which starts at 300 Hz. In addition, tones 11 (97.4
Hz), 39 (69.3 Hz), 40 (206.5 Hz), 41 229.1 Hz), and 42 (254.1 Hz) are normally not used
because they may cause interference with adjacent tones.
A reverse burst is transmitted when the push-to-talk switch is released and also detected
when calls are received. It is a 180-degree phase reversal for a period of time determined
by the tone frequency, and it eliminates the squelch tail (noise burst) in the receiving radio.
Both the transmitting and receiving radio must be equipped with this feature for it to be
used. The radio can be programmed to turn OFF the reverse burst feature so that the
squelch tail is not eliminated.
when calls are received. It is a 180-degree phase reversal for a period of time determined
by the tone frequency, and it eliminates the squelch tail (noise burst) in the receiving radio.
Both the transmitting and receiving radio must be equipped with this feature for it to be
used. The radio can be programmed to turn OFF the reverse burst feature so that the
squelch tail is not eliminated.
If the user would like to hear the squelch tail, then the reverse burst transmission can be
disabled by programming.
disabled by programming.
Preliminary Draft 3/9/12