User's Manual

Draft 02 - Sep 1 2015
Viking Mobile Radio Operating Manual 5-13
Conventional Mode Features
Note 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 (Standard Control Head)
while the “P” is indicated on the top of the screen for the Lightning Control Head 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 on
the Standard Control Head while “P2” is indicated on the Lightning Control Head.
The priority channel sampling frequency is determined 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 conventional scanning. It does not occur with
radio-wide scanning, when listening to any type of SMARTNET/SmartZone/P25 trunking
call, encrypted call, or when transmitting.
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.
Priority Indicator