Ericsson VRC User manual

VRC
Vehicular Repeater
e
Operator’s Manual

This manual is published by Ericsson Inc., without any warranty.
Improvements and changes to this manual necessitated by typographical
errors, inaccuracies of current information, or improvements to programs
and/or equipment, may be made by Ericsson Inc., at any time and without
notice. Such changes will be incorporated into new editions of this manual.
No part of this manual may be reproduced or transmitted in any form or by
any means, electronic or mechanical, including photocopying and recording,
for any purpose, without the express written permission of Ericsson Inc.
The software contained in this device is copyrighted by
Ericsson Inc. Unpublished rights are reserved under the
copyright laws of the United States.
NOTICE!
NOTE!
Repairs to this equipment should be made only by an author-
ized service technician or facility designated by the supplier.
Any repairs, alterations or substitution of recommended parts
made by the user to this equipment not approved by the
NOTICE!
This manual covers Ericsson and General Electric products
manufactured and sold by Ericsson Inc.
Copyright © January 1997, Ericsson Inc.
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SAFETY INFORMATION
The operator of any mobile radio should be aware of certain
hazards common to the operation of vehicular radio transmis-
sions.
A list of the possible hazards are:
1. ExplosiveAtmospheres
Just as it is dangerous to fuel a vehicle with the motor
running, be sure to turn the radio off while fueling the
vehicle. Do Not carry containers of fuel in the trunk of the
vehicle when the radio is mounted in the trunk.
2. Interference To Vehicular Electronic Systems
Electronic fuel injection systems, electronic anti-skid
breaking sys-tems, electronic cruise control systems, etc.,
are typical of the types of electronic devices that may
malfunction due to the lack of protec-tion from radio
frequencyenergypresentwhentransmitting.Ifthevehicle
contains such equipment, consult the dealer for the make
of vehicle and enlist his aid in determining if such elec-
tronic circuits perform normally when the radio is trans-
mitting.
3. Dynamite Blasting Caps
Dynamite blasting caps may be caused to explode by
operating a radio within 500 feet of the blasting caps.
Always obey the "Turn Off Two Way Radio" signs posted
wheredynamiteisbeingused.Whentransportingblasting
caps in your vehicle:
a. Carry the blasting capsin a closed metalboxwith asoft
lining.
b. Leave the radio OFF whenever the blasting caps are
being put into or removed from the vehicle.
4. Radio Frequency Energy
To prevent burns or related physical injury from radio
frequency energy, do not operate the transmitter when
anyone outside of the vehicle is within two feet of the
antenna.
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OPERATING RULES AND REGULATIONS
Two way FM radio systems must be operated in accordance
with the rules and regulations of the Federal Communications
Commission (FCC). As an operator of two way radio equip-
ment, the user must be thoroughly familiar with the rules that
apply to the intended type of radio operation. Following these
rules will help to eliminate confusion, assurethe most efficient
use of existing radio channels, and result in a smoothly func-
tioning radio network.
When using the radio, remember these rules:
1. It is a violation of FCC rules to interrupt any distress or
emergency mes-sage. In conventional mode the radio
operatesinmuchthesamewayasatelephone"partyline"
therefore always listen to make sure that the line is
clear--that no one else is on the air--before sending any
messages. If someone is sending an emergency message-
-such as reporting a fire or asking for help in an accident-
-KEEP OFF THE AIR!
2. Use of profane or obscene language is prohibited by
Federal Law.
3. It is against the law to send false call letters or a false
distress or emergency message.
4. The FCC requires that conversations be brief and con-
fined to business. To save time, use coded messages
whenever possible.
5. Using the radio to send personal messages (except in an
emergency) is a violation of FCC rules. Only those
messages essential for the business operation may be
sent.
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6. It is against the Federal law to repeat or otherwise make
known anything overheard on the radio. Conversations
between others sharing a commu-nications channel must
be regarded as confidential.
7. The FCC also requires that the caller be identified at
certain specific times by means of call letters. Refer to
the rulesthat apply to the particu-lar typeof operation for
the proper procedure.
8. Nochangesoradjustmentshallbemadetotheequipment
exceptby anauthorizedorcertifiedelectronictechnician.
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INTRODUCTION
The Vehicular Repeater Conventional (VRC) is designed
to provide extended portable communication coverage by re-
peating conventional transmissions in both directions through
an existing high power mobile radio.
VRC FRONT PANEL
The VRC has 8 LEDs to indicate the current status of the
repeater:
CPU Flashes at approximately 1 Hz rate to indicate proper
operation of the on-board microprocessor.
Pri Indicates the VRC is at priority status and will repeat
all transmissions, portable-to-base and base-to-port-
able. In multi-vehicle applications, only one VRC/mo-
bile combination should be at priority status.
Repeater
Cor Indicates the VRC is receiving carrier from a portable
(Tone LED should also be on) or another VRC (Cor
LED only).
Tone Indicates the VRC is decoding the sub-audible tone
from the portable. This LED should only be on when
the repeater Cor LED is also on. If the VRC is the
priority unit, the Mobile Tx LED should also be on.
TX Indicates when the VRC is transmitting to the portable.
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Mobile
Cor Indicates that a transmission is being received by the
mobile. If the Pri LED is on, the RptrTx LED should
also be on. If the VRC is not at priority status, theRptr
Cor LED should be on indicating that another repeater
is handling the transmission.
Tx Indicates when the mobile is being keyed by the VRC.
Opt The option LED is used to indicate program mode (on
steady) when the programming cable is inserted, or to
indicateaproblemwiththeradioportionoftherepeater
(rapid flashing). If the Opt LED flashes at approxi-
mately 10 Hz rate, contact your service center.
FUNCTIONAL DESCRIPTION
Generally, vehicularrepeaters areused as mobileextenders
in cross-band operation; i.e., the link is UHF and the mobile
is low band or VHF. In-band operation is possible, but care
must be taken to prevent interference between the mobile’s
higher power transmitter and the repeater receiver. Proper
frequency selection and antennaplacement are important even
incross-bandoperation,butespeciallyforin-banduse.Theuse
of low power pre-selector cavities may be placed in line with
the repeater antenna cable since it is simplex and low power.
The VRC operates on UHF simplex frequencies. The port-
ables must transmit with a CTCSS tone, but should be carrier
squelch receive, or use a decode tone different from the trans-
mit tone. Part of the multi-vehicle format dictates that all of
the VRCs must be able to monitor all link traffic on site and be
able to determine if a portable is transmitting, or if other
repeaters are transmitting.
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When the user leaves the vehicle, the VRC must be acti-
vated via the mobile radio front panel or a separate switch.
When the mobile radio is receiving carrier and proper CTCSS
tone, the VRC will begin transmitting on the portable’s receive
frequency. The user is able to hear and respond to all radio
messages, including other portables at the site. The VRC can
be programmed to give the portables priority in a conversation
by periodically sampling for portable activity (carrier and
proper CTCSS tone) during base-to-portable transmissions.
During sampling, if the VRC detects a portable transmission,
it will cease transmission, key the mobile radio and repeat
portable-to-base. This allows the portable to respond during
repeater hang time or during full duplex interconnect calls.
Priority sampling can be enabled/disabled through PC pro-
gramming and interval can be programmed between 0.25
seconds and 2.5 seconds in 0.25 second increments.
The VRC has a fixed 3-minute time out timer for base-to-
portable transmissions. If the mobile carrier operated relay
(COR) is active for more than 3 minutes (and the VRC is the
priority unit), the VRC will send a double blip and cease
transmission until the mobile COR is inactive. The 3 minute
time-out is in effect regardless of whether the VRC is pro-
grammed for priority sampling or not.
MULTI-VEHICLE OPERATION
When the VRC is first activated, it will transmit a short
“lock tone” that alerts the user that the system is functioning.
It will then assume the priority status and be ready to repeat
any base-to-portable or portable-to-base transmissions. If an-
other unit arrives on scene and is activated, it too will transmit
a “lock tone”. WhenthefirstVRC detectsthe“lock tone”from
the second unit, it will increment a “priority counter” and will
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no longer repeat any transmissions. The recently arrived unit
will be the priority repeater, and the first unit will be one count
away from priority. This process will continue for each unit
that arrives at the scene, creating a priority hierarchy for up to
256 vehicles, each with a unique count and only one unit at
priority status. TheVRC will not transmit it’s “lock tone’if the
radio channel is busy when first enabled. It will wait in non-
priority status until alltransmissions cease, then send it’s “lock
tone” and become the priority unit.
Even though the other VRCs are not a priority status, they
will continue to monitor the channel for activity. If the priority
unit leaves the scene or becomes disabled, the other units will
detect the condition to repeat and determine that there is no
priority unit repeating the transmission. They will then begin
decrementing their priority counters until one of them reaches
the priority status and begins repeating the transmission. Since
theVRCsareallatdifferentcounts,onlyonewillreachpriority
status and begin transmitting. The other units will sense the
new priority repeater and cease counting down, preserving the
priority hierarchy.
If another unit were to arrive from a different scene and it
is still the active priority, there will be two active repeaters on
theairwhenaconditiontorepeatexists.WhenoneoftheVRCs
unkeys to check for portable activity, itwill detectthe presence
of the other active VRC and increment it’s priority counter and
cease transmission. This is the self-clearing mode to prevent
radio interference.
Iftheportableuserisoutofthevehicleandthemobileradio
is keyed by the local microphone inside the vehicle, the VRC
will detect the local PTT and repeat the transmission to the
other portables so that both sides of the conversation will be
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heard by everyone on the link. The local microphone repeat
function can be enabled/disabled via PC programming.
The VRC also has a local receive audio speaker jack that
enables a person inside the vehicle to monitor portable-to-base
transmissions that are being repeated through the mobile.
Ifportableuserswishtocommunicateportable-to-portable
without accessing the mobile VRC repeater, the may transmit
on the same frequency without CTCSS tone (or a different
CTCSS tone); the VRC only responds to carrier and proper
CTCSS tone from the portables.
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