GE LBI-31154 Maintenance Manual page 9

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VEHICULAR REPEATER SYSTEM DESCRIPTION
LB131154
unit, etc.) the REPEATER pushbutton
0
switch mustbe manually operated to the
"on" and "off" positions.
-
The microcomputer in each vehicular
repeater utilizes a random
counter to
establish priority.
The counter is
started each time a condition to repeat
is detected. If no repeater begins to
repeat before the counter counts down the
repeater will begin to repeat and will
assume the priority state.
All other
The counter repeaters will remain quiet.
consists of a fixed 400 millisecond delay
and a random count of 1.1 seconds.
Since
the value of the count is initialized
when the repeater is tuned on, each indi-
vidual
repeater will have a different
delay which will change each time the
repeater is powered up.-
A Carrier Control Timer (CCT) which
resides in microcomputer software,
pre-
vents system tie-ups by timing base-to-
portable transmissions.
A DA jumper wire
Hl-H2 may be connected to disable the CCT
if desired.
Courtesy Beep
The Type 90 encoder is enabled for
approximately 30 milliseconds at the end
of each portable-to-base repeat transmis-
sion.
This tone burst or courtesy beep
lets the portable operator know that his
radio is working and his message has been
transmitted to base. It may be desirable
to eliminate the courtesy beep in systems
using both the lQC331423 logic board and
the lQC328461 logic board. Because of
the different method used to establish
repeater priority in vehicular repeaters
using logic board lQC328461 its possible
that the courtesy beep could cause all
repeaters so equipped to count down
simultaneously the eight levels of prior-
ity. This would allow all repeaters
equipped with the lQC328461 logic board
to temporality assume priority status.
For this reason a DA-jumper wire may be
connected between H5-H6 on the lQC331423
logic board to disable the courtesy beep.
Vehicular Repeater System Enable
When a vehicle containing the Vehi-
cular Repeater system equipment arrives
at a location that requires the operator
to be away from the vehicle and get main-
tain communication,
the Vehicular
Repeater System can be
enabled.
Normally,
the PE radio is inserted in the
vehicular charger
and the REPEATER
pushbutton
switch is in the "on"
position.
The operator, when removing
the PE radio,
automatically enables the
Vehicular Repeater System.
The mobile
radio
will operate on the
channel
indicated by the control unit.
The PE
radio channel select switch should be set
to the
designated repeat channel
position.
When the PE radio is removed from
the vehicular charger unit, a switch
closure in the vehicular charger causes a
repeat enable signal to be applied to. the
logic circuitry in the vehicular repeater
radio. This, in turn, causes the vehicu-
lar repeater to transmit a 700 milli-
second burst of Type 90 tone. Since no
other Vehicular Repeater Systems have
been enabled at this time the Type 90
tone burst has no effect. At the time of
the Type 90 tone burst, the microcomputer
established the repeater as the priority
repeater.
REPEATER PRIORITIZING AND OPERATION
The vehicuiar repeater contains a
prioritizing system to prevent more than
one radio from transmitting at once.
When a repeater is enabled,
it will
transmit a 700 millisecond Type 90 tone
on the portable frequency and goes into
the "priority state". In priority, the
repeater will repeat as soon as a request
to repeat is heard. A vehicular repeater
always listens ~for the Type 90 tone on
the portable frequency. If it hears the
tone, the repeater assumes that another
repeater has just been enabled and is
therefore the priority repeater.
All
repeaters who hear the tone will immedi-
ately jump to the "non-priority state".
A repeater in non-priority will not
repeat immediately. It will listen for
another repeater to come up. If no other
repeater begins to repeat within a
specified time period,
the non-priority
repeater will assume that there is no
priority repeater present to repeat.
The
non-priority repeater
will begin to
repeat and jump into the priority mode to
become the new priority repeater.
The
specified time period is random and will
vary from repeater to repeater. The
random delay is between 400 ms and 1.1
seconds long. (The random clock is
loaded with a different setting each time
a request to re_peat is heard.) In a
system that is functioning correctly,
there can be any number of non-priority
repeaters, but only one repeater will be
in priority, and it will be the one doing
all of the repeating.
If the priority repeater leaves the
scene,
when the next request to repeat
comes along a ehort random time delay
will occur before one of the remaining
repeaters will step up to the priority
state and start to repeat. All of the
other repeaters will remain silent, and
stay in non-priority.
The microcomputer will recognize the
following conditions as repeat require-
ments.