Draft 02 - Sep 1 2015
5-2
Viking Mobile Radio Operating Manual
Conventional Mode Features
Busy Indicator
- With scanning disabled, note if the multi-function indicator on the
front panel is steady green. If it is green, a carrier is being detected, so the channel may
be busy. If it is not, the channel is not being used and a call can be transmitted.
Monitor Mode
- There may be times when the busy indication is displayed even
though no one is using the channel. Monitoring should then be performed by disabling
Call Guard squelch (or group ID detect on P25 channels). This is usually done by
selecting the Monitor Mode (see following) or by the Normal/Selective option switch
(see Section 5.4.1).
5.2
Monitor Mode
The monitor mode unsquelches the receiver and monitors the channel even if a carrier is
not detected. Other features of this mode are as follows:
• Call Guard (CTCSS/DCS) squelch is disabled on analog channels and NAC and group
ID detect are disabled on P25 (conventional) channels.
• Signalling-dependent Busy Channel Lockout options for Tone/NAC and P25 status are
ovrerridden (see next section). (Noise option is not overridden: Monitor mode disables
the protocol-signalling events that the Busy Channel Lockout option Tone/NAC/Status
depend on, but not carrier events.)
• Scanning temporarily halts.
The Monitor Mode operates as follows:
1
To monitor the transmit frequency for activity before transmitting, briefly press the
Monitor option switch. The display then indicates “MON” (see Figure 2.3) for the
Standard Control Head or
for the Lightning Control Head. The receiver
unsquelches and noise is heard even if carrier not present. The transmit frequency can
also be monitored by selecting
TX Channel
in the Monitor menu function’s sub menu.
2
To monitor the receive frequency instead, press and hold the Monitor option switch
until a tone sounds (based on radio programming). This can be used, for example, to
improve reception if intermittent squelching is making a weak message difficult to
understand.
3
To disable the monitor mode and return to normal operation, press the Monitor option
switch again (or select
Off
from the menu).
If off-hook detection is enabled, taking the microphone off-hook monitors the receive
frequency similar to Step 2. However, the receiver unsquelches only if a carrier is detected
(see Section 4.9). Pressing the Normal/Selective option switch disables Call Guard
squelch/P25 group ID detect but not scanning and P25 NAC detect (see Section 5.4).
