System Operation - GE LBI-31154 Maintenance Manual

LB131154 VEHICULAR REPEATER SYSTEM DESCRIPTION
I NoTE I
The vehicular repeater should
not be used with gain antennas.
Also, for improved operation,
the distance between the mobile
and repeater antennas should be
maximized.
When the Vehicular Repeater System
is enabled, the mobile radio is used to
repeat transmissions to and from remate/
repeat base stations. This arrangement
permits cross-band repeat operation to
minimize interference
problems and
eliminate the requirements for duplexers.
The mobile radio control unit allows
the operator to select one of up to eight
operating channels for mobile-to-base
communications.
The vehicular charger contains the
control circuitry to apply power to the
vehicular repeater radio, to enable the
Vehicular Repeater System,
and to re-
charge the battery pack of the PE radio.
During normal mobile operation the PE
radio is inserted into the vehicular
charger and the REPEATER pushbutton
switch set to the "on" position.
This
places the Vehicular Repeater System in a
ready condition so that removal of the PE
radio unit automatically enables the
Vehicular Repeater System.
Power is automatically applied to
recharge the battery pack when the PE
radio is inserted into the charger.
The
amber LED indicator labeled CHARGE will
glow when positive contact has been made
and the green LED indicator labeled READY
will glow when the battery pack
is
fully
recharged.
The PE radio operates in the 138-
174 MHz or 406-512 MHz frequency range
with a medium power transmitter and using
a flexible spring antenna.
A channel
selector switch permits selection of up
to 8 channels.
Only one frequency chan-
nel is-,-used to communicate via the
vehicular repeater.
SYSTEM OPERATION
The
Vehicular ~Repeater System
'extends the communications from a fixed
mobile
(vehicle)
system to a portable
communications
system permitting the
vehicle operator to remain in continuous
communication with the dispatch center or
other radio system units when away from
the vehicle.
There are three basic types
of operation possible when the operator
has left the vehicle with the PE radio.
One is portable-to-base operation which
uses the Vehicular Repeater System to
repeat any transmissions from the PE
radio to a remote/repeat base station for
communications with a dispatcher or to
other mobile radio units via a base
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station repeater facility.
Another type of operation is the
base-to-portable wherein a dispatcher(s)
or other mobile radio units using a
remote/repeat base station can communi-
cate with the PE 'radio operator through
the repeat function of the Vehicular
Repeater System.
The third type of operation involves
the PE radios for portable-to-portable
communications without activating the
repeater.
In portable-to-base operation the
Vehicular Repeater System is enabled.
When the PE radio user has the channel
select switch on the designated repeater'
channel and keys the unit, the transmit-
ted signal is modulated with a Channel
Guard tone. When this CG tone is
detected by the CG decoder in the Vehi-
cular Repeater radio, the microcomputer
on the logic board keys the mobile radio
transmitter.
The Vehicular Repeater system is
interrupted when the mobile microphone is
used. When the mobile PTT switch is
operated the repeat function is disabled
and the mobile radio is used for communi-
cations. When the mobile microphone use
0
is concluded, the Vehicular Repeater
System will again be available for the
repeat function. However, since repeater
priority is random as established by
software control,
an alternate repeater
system may assume priority status.
The base-to-portable operation is
the reverse of the portable-to-base
operation described above.
During these two operations all PE
radios in the area will hear each other's
transmissions directly and the repeated
reply from the base station.
The thirdtype of op-eration involves
only the PE radio units and does not
require the repeating functions of the
Vehicular Repeater System. A designated
channel not provided with the repeater CG
tone is used for direct portable-to-
portable communications. Since it does
not contain a CG tone, it cannot activate
the vehicular repeater. However, all PE
radios in the area and on the designated
channel will hear the transmissions.
Returning the PE radio to the charg-
ing insert on-&e vehicular charger auto-
matically disables the Vehicular Repeater
System. Should the PE radio not be in-
serted into the vehicular charger for
0
some reason (e.g., servicing, wearing of
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