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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

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.

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.