CONVENTIONAL FEATURES
31
analog channel on the same frequency as the priority
channel and is programmed with CTCSS/DCS squelch
control.
Either a single or dual priority* channels can be
programmed if desired. With dual priority, a call on
the second priority channel is interrupted by a call on
the first priority channel but not vice versa. When
scanning and the selected channel is a single or first
priority channel, “
P
” is indicated in the left status
display next to the zone number as follows:
This indication is displayed regardless of whether
the priority channel is fixed or always the selected
channel. When the second priority channel is
displayed, “
2
” is indicated instead.
The priority channel sampling frequency is deter-
mined by the programmed Priority Lookback Time A
(see description which follows). For example, if 2.0
seconds is programmed, the priority channel is
sampled every 2.0 seconds when listening to a
message on a non-priority channel. When not listening
to a message, the priority channels are scanned in the
normal scan sequence. With dual priority, the first and
second priority channels are alternately sampled at the
Loopback Time.
Priority channel sampling occurs only with stan-
dard conventional scanning. It does not occur with
radio-wide scanning, when listening to any type of
SMARTNET/SmartZone/P25 conventional or trunked
call, encrypted call, or when transmitting. A series of
“ticks” may be heard when the priority channel is
sampled while listening to a message on some other
conventional channel.
The priority sampling times are programmed by
the following parameters:
Lookback Time A -
This time determines how often
the priority channel is checked for activity. Times of
0.25-4.00 seconds in 0.25-second steps can be
programmed.
Lookback Time B -
This time determines how often
the priority channel is checked once an incorrect Call
Guard (CTCSS/DCS) or NAC code is detected. Since
it takes much longer to detect an incorrect Call Guard
signal than a carrier, this time should be relatively long
to prevent the interruptions from making a message
difficult to understand. Times of 0.5-8.0 seconds can
be programmed in 0.5-second steps.
Changing The Priority Channel
If a fixed priority channel is associated with the
current scan list, it can be changed to another channel
if the
PRI ED
option switch is programmed. With dual
priority, this changes only the first priority channel. To
change both priority channels, use the Scan List Edit
function described in Section 4.12.1. Proceed as
follows to change a priority channel using the
PRI ED
option switch:
1. Make sure that both priority and radio wide scan-
ning are off (the rotating icon is not indicated in
the right status display).
2. Select the channel that you want to be the priority
channel using the Select switch in the normal
manner. If the channel is in a different zone, also
select the appropriate zone.
3. Press the
PRI ED
option switch and “Priority” is
briefly displayed to indicate that the selected
channel is now the priority channel. Other indica-
tions that may occur are as follows:
•
If “No Priority” is displayed, priority sampling
may not be enabled on the scan list.
•
If “Sel Chan” is displayed, the priority channel is
always the selected channel and cannot be
changed.
•
If no indication displayed, the scan list may not be
user editable or the channel may not be in the scan
list.
5.12 STANDARD CONVENTIONAL CALLS
Standard conventional calls can be placed to other
mobile units monitoring the selected channel. The
proper coded Call Guard squelch tone or code or P25
Priority Indicator
*
This feature requires firmware Version 1.17/2.0/3.0/4.2
or later.
