E.F. Johnson 5100 SERIES Service Manual - page 25
OPERATION
2-14
September 2001
Part No. 001-5100-001
No Priority -
No priority channel sampling occurs
when the list is selected. The radio transmits on the
selected channel.
Priority/Tx Priority -
Priority sampling occurs and
the priority channel is the one programmed in the
selected scan list. The radio transmits on the priority
channel.
Priority/Tx Selected -
Priority sampling occurs and
the priority channel is the one programmed in the
selected scan list. The radio transmits on the selected
channel.
Priority on Selected -
The priority 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.
2.6.13 PRIORITY CHANNEL SAMPLING
General
The priority channel sampling feature ensures
that when standard scanning is occurring, messages on
the priority channel are not missed while listening to a
message on some other channel. Your transceiver can
be programmed so that the priority channel is a fixed
channel associated with the current scan list, the
currently selected channel, or not used. When the
selected channel is a priority channel,
“Pri”
is indi-
cated in the upper part of the display.
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 call, or when transmitting. A
series of “ticks” may be heard and the indicator on the
top panel flashes green when the priority channel is
sampled while listening to a message on some other
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 specific priority channel is associated with
the current scan list, it can be changed if the Priority
option switch is programmed. Proceed as follows:
1. Select the scan list number to be edited as described
in Section 2.6.12. If a list is not selected, the last
active scan list is automatically edited.
1. Make sure that both radio-wide and standard scan-
ning are off (“
Scan
” is not indicated in display).
2. Select the channel that you want to be the priority
channel using the channel selector switch on the top
panel. If the channel is in a different zone, also select
the appropriate zone.
3. Press the Priority option switch and the “
Pri
” is
displayed to indicate that the selected channel is
now the priority channel.
2.6.14 PLACING AND RECEIVING STANDARD
CONVENTIONAL CALLS
Standard conventional calls are calls to or from
other mobile units on the selected channel. The proper
coded Call Guard signaling (see Section 2.6.6) may
need to be transmitted for them to receive your call
and also for you to receive their calls. Proceed as
follows to place and receive these calls:
Placing a Standard Conventional Call
1. Turn power on and set the volume as described in
Section 2.4.2. Select the channel programmed for
the mobile you want to call (see Section 2.4.8).