Transmitting In Scan Mode; Priority Channel Sampling - E.F. Johnson Company 4100 SERIES Operating Manual

5.11.2 TRANSMITTING IN SCAN MODE

Each conventional scan list can be programmed
for one of the following modes. These modes deter-
mine if priority sampling occurs and also the channel
on which transmissions occur while scanning. Refer to
the next section for more information on priority
sampling.
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
transmits 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.

5.11.3 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.
General
The priority channel sampling feature ensures
that when priority 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: The priority channel is not scanned if the
active channel is an analog channel on the same
CONVENTIONAL MODE FEATURES
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,
indication is displayed regardless of whether the
priority channel is fixed or always the selected
channel. When it is a second priority channel,
displayed.
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
Lookback Time.
Priority channel sampling occurs only with
conventional priority scanning. It does not occur with
radio wide scanning, when listening to any type of
SMARTNET/SmartZone/P25 trunked call, encrypted
call, or when transmitting (see preceding note). 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.
32
is indicated in the display. This
is
2