User's Manual

CONVENTIONAL FEATURES
30
No Priority - No priority channel sampling occurs
when the list is selected. The radio transmits on the
selected channel.
Priority/Tx Selected - Priority sampling occurs and
the priority channel or channels are those programmed
in the selected scan list. The radio transmits on the
selected channel.
Priority/Tx Priority (1) - Priority sampling occurs
and the priority channel or channels are those
programmed in the selected scan list. The radio trans-
mits on the priority (1) channel.
Priority (1) on Selected - The priority (1) channel is
always the selected channel. The radio transmits on
the selected channel.
Talkback - No priority sampling occurs. The radio
transmits on the channel of a call while scanning is
halted. Then once scanning resumes, it transmits on
the selected channel.
5.11.4 PRIORITY CHANNEL SAMPLING
NOTE: The following describes priority sampling
when scanning conventional channels. Priority
sampling when scanning SMARTNET/SmartZone/P25
Trunked channels is described in Section 6.12.2.
General
The priority channel sampling feature ensures
that when standard scanning, messages on the priority
channel are not missed while listening to a message on
some other channel. The radio can be programmed as
just described so that the priority channel is a fixed
channel programmed in the current scan list, the
currently selected channel, or not used.
NOTE: Priority channel sampling is not available
when receiving analog encrypted (DES/DES-XL) calls,
and also when receiving P25 calls if equipped with
ARM firmware 1.23 or earlier. In addition, the priority
channel is not scanned if the active channel is an
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
Priority Indicator
* This feature requires 5300 firmware 1.17/2.0/3.0 or
later.