User's Manual

CONVENTIONAL FEATURES
20
Revised August 2002
Part No. 001-5300-007CD-NR
before transmitting or improving reception when inter-
mittent squelching makes messages hard to under-
stand. Other Monitor mode features 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.
• Busy Channel Lockout is overridden (see next
section)
• Scanning temporarily halts
The Monitor Mode is selected as follows:
1. Briefly press the
MON option switch (if available).
The display then indicates “MON” (see Figure 2-3
on page 8) and the receiver unsquelches.
2. To disable the monitor mode and return to normal
operation, press the
MON option switch again.
3. In the scan mode, pressing and holding the
MON
option switch monitors the scanned channel instead
of the selected channel (if it is different).
Taking the microphone off-hook also selects the
Monitor mode if off-hook detection is enabled (see
Section 3.15). Pressing the
SEL SQ option switch
disables Call Guard squelch/P25 group ID detect but
not scanning and P25 NAC detect (see Section 4.5).
4.4 BUSY CHANNEL LOCKOUT
The Busy Channel Lockout (also called Transmit
Disable on Busy) feature automatically disables the
transmitter if the channel is busy when the PTT switch
is pressed. When the transmitter is disabled by this
feature, “BUSY” is displayed, a busy tone sounds, and
the transmitter is disabled.
The Busy Channel Lockout feature can be
programmed to operate as follows. Each conventional
channel can be programmed differently.
Off - Busy channel lockout is disabled and the trans-
mitter keys even if the channel is busy.
Noise - If a carrier is detected on the channel, the
transmitter is disabled when the PTT switch is pressed.
Tone (NAC) - If an incorrect Call Guard (CTCSS/
DCS) or P25 NAC code (see Section 1.4) is detected,
the transmitter is disabled when the PTT switch is
pressed. An incorrect code is any code other than the
one programmed for the current channel.
If Busy Channel Override is permitted by
programming, it is possible to transmit even when the
transmitter is disabled by this feature. Simply release
the PTT switch and then quickly press it again.
4.5 CALL GUARD SQUELCH
4.5.1 INTRODUCTION
Tone or digital Call Guard squelch (also called
CTCSS/DCS signaling) can be programmed on each
conventional analog transmit and receive channel in
any order desired. The reverse burst and turn-off code
are always transmitted and also detected on channels
programmed with Call Guard squelch.
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 atten-
uated by a filter. Call Guard squelch must be used in
both the transmitting and receiving transceiver to be
functional.
4.5.2 CALL GUARD SQUELCH ENABLE/
DISABLE
The SEL SQ option switch (if programmed) can
be used to disable receive Call Guard squelch on
analog channels or group ID code detect on P25 chan-
nels. When selective squelch is disabled, “NORMAL”
is flashed in the display, and when it is enabled,
“SELECTIVE” is flashed.
When “Normal” is selected, the receiver
unsquelches only if a carrier is detected, and scanning
and P25 NAC detection are not disabled. The selected
mode remains in effect until it is manually changed.
Selecting another channel or cycling power does not
reselect a default condition.