Service manual

OPERATION
3-8
April 2001
Part No. 001-9800-203
“SQUELCH” on the top line of the display, and the
relative squelch level is indicated by a bar graph on
the bottom line.
4. To select the current level and exit the mode, press
the AUX1/AUX2 (low tier) or Select (high tier)
switch again. This also occurs automatically 2
seconds after a change is made or 8 seconds after no
activity.
NOTE: Some readjustment may be required if weak
messages are not heard or unsquelching occurs when
no messages are present.
3.4.7 LTR AND CONVENTIONAL OPERATING
MODES
Introduction
This transceiver can be programmed to operate in
the LTR and conventional modes. Each selectable
system can be programmed for either of these modes.
The operation that is programmed is determined by the
type of repeater equipment being used. The differences
in operation are described in the following information
and also noted elsewhere as required.
LTR Operation
The LTR mode provides automatic channel selec-
tion (trunking) and monitoring before transmitting.
Special tones and display messages indicate busy and
out-of-range conditions, and telephone calls can be
placed almost as conveniently as with your home tele-
phone. The types of calls that can be placed are stan-
dard (mobile-to-mobile) and telephone. Standard calls
are described in Section 3.8.4, and telephone calls are
described in Section 3.8.5.
In the LTR mode, selecting a system selects a
collection of groups and other information. Selecting a
group selects transmit and receive ID codes and other
information pertaining to that group such as Call indi-
cator and horn alert operation. The ID codes determine
the type of call (mobile-to-mobile or telephone) and
the mobile or group of mobiles being called and what
calls are received. The system may also be
programmed with priority and block ID codes that
allow additional calls to be received. For more infor-
mation on LTR features, refer to Section 3.8 and LTR
Application Note, Part No. 009-0001-020, rev. 8 or
later.
Conventional Operation
In the conventional mode, selecting a system
selects a block of up to sixteen channels, and selecting
a group selects the channel. Each channel (group) can
be programmed for a different squelch control tech-
nique (CTCSS, CDCS, external decoder, or carrier)
and other parameters. The squelch level must be
adjusted as described in Section 3.4.6 to properly
receive conventional calls.
With conventional operation, a busy condition is
detected automatically if the Transmit Disable On
Busy feature is used (see Section 3.9.2). Otherwise, it
must be detected manually as follows. An out-of-range
condition is not indicated by a special tone or display
message because there is no data handshake with a
repeater that allows this condition to be detected.
Refer to Section 3.9 for more information on conven-
tional operation.
To manually monitor a channel before transmit-
ting to determine if it is being used by someone else,
proceed as follows:
NOTE: The busy indicator and monitor mode icon are
not available with low tier models.
Using Busy Indicator (high tier only) - With scan-
ning disabled and the squelch control adjusted as
described in Section 3.4.6, note if the indicator on the
front panel is lighted green. If it is, a carrier is being
detected on the currently selected conventional group
(channel). If this indication is not present, the channel
is not busy and the message can be transmitted.
Using Monitor Mode - If scanning, take the micro-
phone off-hook to disable scanning and enable the
monitor mode (indicated by in the high tier
display). The monitor mode can also be enabled by
pressing an option switch programmed for the monitor
function. The monitor mode disables squelch control
features so that all messages are heard. If none are
heard, the channel is free and the message can be
transmitted. Refer to Section 3.9.1 for more informa-
tion on monitoring.