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Viking™ VP600 Portable Radio Operating Manual
5-5
Conventional Mode Features
5.4.5 Conventional Squelch Adjust
Squelch settings on a conventional analog channel can be changed by the user from -7 to 
+7. A menu item or function button can be programmed for squelch adjust. While on a 
conventional analog channel without emergency or scan active, the user can select the 
programmed button or menu item for squelch adjust. The current squelch setting will 
show on the display.
Using the up and down buttons on the portable, the user can adjust the squelch setting to a 
desired level from -7 to +7. Increasing the value towards +7 causes the squelch to open 
sooner for weaker signals while decreasing towards -7 has the opposite effects. Pressing 
the select button will store the new squelch setting and return the user to the main display.
5.4.6 Selective Squelch Code Select (CTCSS / DCS / NAC)
This feature allows the normal transmit and receive Call Guard (CTCSS/DCS/NAC) 
programming to be temporarily overridden with a code selected from a pre programmed 
list. It is available if the Squelch Select List option button or menu parameter and a 
CTCSS/NAC code list have been programmed.
Note
Call Guard codes can be permanently reprogrammed by keypad programming described 
in Section 5.14, "Keypad Programming".
In addition, conventional systems can be programmed for the Keypad CTCSS/DSC 
feature. Codes can then be selected directly from the table by pressing the key for the 
code. For example, to select code 3 from the table, press the “3” key. No other 
conventional mode functions can then be assigned to these keys.
The CTCSS/DCS/NAC list is programmed with up to 255 tone (CTCSS) or digital (DCS) 
Call Guard codes. Different codes can be programmed for the transmit and receive modes, 
and carrier squelch (selective squelch disabled) can be programmed if desired. In addition, 
each position can be programmed with a NAC code for use with P25 operation.
When the Call Guard code is changed using this feature, it remains selected even if other 
channels are selected. However, if radio power is cycled or a talk-around channel is 
selected, the normal codes are reselected. When scanning, the selected code also applies to 
all scanned channels. Each channel can also be programmed to always ignore the code 
selected from this list and use the default code instead.
If both analog and digital (Project 25) channels can be selected or scanned, the CTCSS/
DCS code for the selected position is used for analog channels and the NAC code for the 
selected position is used for P25 channels. If a channel is programmed for mixed mode 
operation, the selective squelch type (analog or digital) programmed for the transmit mode 
determines the selective squelch type used.
Proceed as follows to select a code using the Squelch Select List option button or menu 
parameter: