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2. To monitor the receive frequency instead, press and
hold the Monitor option switch until a tone sounds
or approximately 2 seconds, or select the Monitor
menu "Sqlch Ovrd" parameter. 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 of
select the Monitor menu "Off" parameter.
The Normal/Selective function disables Call
Guard squelch and P25 group ID detect but not
scanning and P25 NAC detect (see Section 5.5.5).
5.4 BUSY CHANNEL LOCKOUT
The Busy Channel Lockout feature (also called
Transmit Disable on Busy) 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 NAC code (see Section 5.16) 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.
CONVENTIONAL MODE FEATURES
5.5 CALL GUARD SQUELCH
5.5.1 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.
5.5.2 CALL GUARD SQUELCH ENABLE/
DISABLE
The Normal/Selective option switch or menu
parameter (if programmed) can be used to disable
receive Call Guard squelch on analog channels or
group ID code detection on P25 channels. When selec-
tive 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, and scanning
and Project 25 NAC detection are not disabled. The
selected mode is in effect until it is manually changed
again. Selecting another channel or cycling power
does not reselect a default condition.
5.5.3 TONE CALL GUARD SQUELCH
Tone-type Call Guard squelch utilizes 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.
25
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