FMC88108-6 Application Note

Overview

These channelised repeaters may be used for providing coverage enhancement in poor signal areas for FM broadcast transmissions. The FMC88108-6 is a multi-channel RF head-end that can provide transmission through antenna, catenary wire or radiating cable signal distribution systems.

FM Radio Rebroadcast System - FMC88108-6

FMC SeriesFM REBROADCAST

The FMC88108-6 provides an easy, cost effective solution for extending the coverage of existing FM broadcast radio stations into coverage black-spots – including campus and office buildings, underground carparks, road and rail tunnels, and mines.

The FMC88108-6 can be used as a FM radio (87.5-108 MHz) rebroadcast system for use in road and rail tunnels, mines, inside buildings, underground car parks and other locations where the availability of existing FM broadcast radio coverage is limited.

This unit can be used to provide the rebroadcast of up to 6 channels, or multiple units can be combined together for larger channel capacity requirements. The per-carrier RF output power of the system can be determined by choosing from our range of FM RF power amplifiers.

SINGLE UNIT APPLICATION

An FM off-air antenna is suitably located to receive donor signals from the FM transmitter that is to be rebroadcast. A simple collinear or dipole antenna, coupled with suitable lightning protection and coaxial cable grounding design principles is ideal for this purpose.

The coaxial cable feed from the off-air antenna is connected to the FMC88108-6 which is programmed for the desired rebroadcast frequency(s).

MULTI-UNIT APPLICATION

As in the single unit application, an FM off-air antenna is suitably located to receive donor signals from the FM transmitter that is to be rebroadcast. The coaxial cable feed from the off-air antenna is connected to a multi-output receiver multicoupler (FM-RMC-1), providing separate off-air antenna signals for multiple FMC88108-6 units.

The RF outputs of the multiple FMC88108-6 units can be combined together to provide a single, multi-channel, RF output for connection to the chosen RF power amplifier.

MULTIPLE BORE / MULTIPLE ZONE APPLICATIONS

Multiple FMC88108-6 units may also be utilised to cater for multiple bore and/or multiple zone rebroadcast systems to suit larger tunnel requirements.

TYPICAL AM REBROADCAST IN A ROAD TUNNEL

ANTENNACATENARY WIRE,OR RADIATING CABLEFMC88108-6

HIGHER POWERED RF OUTPUTS

The RF output(s) of a FMC88108-6 based design can be connected to additional RF power amplifiers to provide higher RF levels if required. In this way, the rebroadcast systems RF output level can be enhanced to provide coverage for the longest tunnels, mines, and in-building and car park areas.

AUDIO BREAK-IN

The FMC88108-6 repeater also provides the ability to interrupt the rebroadcast signal and to insert an audio signal. This “audio break-in” functionality allows live or pre-recorded announcements to be placed onto the rebroadcast RF outputs for incident control and public safety purposes.

In mining applications, such messages may be used to provide emergency announcements. In road or rail tunnels, such messages could be used to advise of accidents, planned maintenance, changed road conditions or even updated timetabling.

FMC88108-6 based multi-bore and/or multi-zone designs provide for such audio break-in announcements to be actioned onto any or all bores and zones – providing flexibility for announcing messages to relevant areas, as required by operational requirements.

RF-OVER-FIBER INTERFACING

Linking technologies such as RF-Over-Fiber (RFOF) are also available in the RFI rebroadcast product range and can be easily implemented into an FMC88108-6 based rebroadcast system to allow the off-air antenna, headend and in-tunnel node equipment locations to be separated from each other by long distances – up to many kilometres. This allows the rebroadcast system headend equipment to be conveniently located where suitable donor signals can be received, and then distributed to a remote location – such as below-ground areas of a mine, or to a distant road tunnel. RFI has a range of RFOF transceivers, including hot/stand-by and auto re-routing models, suited to a range of applications and design configurations.

In this diagram, twelve (12) FM channels are being rebroadcast into two (2) separate bores of a road tunnel project. Separate “bore1” and “bore2” RF outputs are provided to feed in-tunnel radiating cable distribution systems, and separate break-in audio circuits allow announcements to be made onto either or both of tunnel bores – i.e. northbound or southbound traffic.

TYPICAL MULTI-CHANNEL FM REBROADCAST FOR A ROAD TUNNEL

FILTER

DIVIDER

LNA

2- WAY COMBINERS

PA88108RF POWER AMPLIFIER

PA88108RF POWER AMPLIFIER

FM-RMC-1

OFF-AIRANTENNA

BREAK-IN AUDIO “BORE 1”

BREAK-IN CONTROL “BORE 1”

BREAK-IN AUDIO “BORE 2”

BREAK-IN CONTROL “BORE 2”

FM REBROADCAST RF O/P “BORE 1”

FM REBROADCAST RF O/P “BORE 2”

TYPICAL AM REBROADCAST IN A ROAD TUNNEL

12 CHANNELS2 BORES

4 x FMC88108-6

Off-AirAntenna

Off-AirAntenna

Off-AirAntenna

A M3 CH

FM12 CH

VHF80 MHz160 M Hz

3 CH

ChannelisedRebroadcastEquipm ent

PMCS Interface

AudioShaper/

Processor

MessageInterposing

Player &Recorder

MessageSelection

Break-In Audio & Control

Supervisory M onitoring & Alarms

Audio Break-In/Message

PA System Control Panel

Link Circuits

Remote Control Room

EXAMPLE MULTI-BAND, MULTI-CHANNEL REBROADCAST DESIGN FOR A TWIN-BORE ROAD TUNNEL

Remote

Digital I/O E&MAlarm I/O Node

Diagnostics

TCB

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-UHF

400 4206 CH

UHF400-420

2 CH

UHF450-470

6 CH

FM/V

HF/

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Off-

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9-99

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N/BAM RF

S/BAM RF

N/BFM/80/160/UH F

S/BFM/80/160/UH F

AM/FM/80/160/UHF Combiners

230m LDF4RN-50A

230m LDF5RN-50A

230m LDF4RN-50A

230m LDF5RN-50A

2x RXL 41-RNTRadiating Cables

50 OhmTermination

50 OhmTermination

In-Tunnel Radiating Cable

= RF

= Power

= Audio

= Control

= Lightning Protector

= GND Kit

Control Room

Comms Room

Audio Break-In/Message PA System Control Panel

Audio Break-InVoice Recording

Logging Subsystem

STATUS AND ALARM MONITORING

The FMC88108-6 provides status and alarm monitoring capabilities. The unit’s internal operation is self-monitored and out-of-tolerance conditions are made available as a dry-contact alarm output for connection to an external monitoring system.

MULTI-BAND AND MULTI-TECHNOLOGY CAPABILITIES

RFI has a wide range of rebroadcast repeaters available. These include models suitable for AM and FM broadcast, VHF/UHF/7/8/900MHz paging and two-way radio, GPS, Satcoms, and cellular. RFI’s rebroadcast products can be implemented to create system designs suited to almost any application, including the rebroadcast of most of the analogue and digital technologies in use in modern wireless communications systems. Such systems can include multiple channels of rebroadcast covering many frequency bands. Enhancements such as full Audio Server functionality for the break-in of live, stored and pre-recorded messages (with full audio, time and date logging) are also available, along with OMCS/PMCS PLC or TCPIP (with single or redundant NICs) interfacing, PA System/EWIS interfacing and control, remote and off-air rebroadcast monitoring, operator consoles, computer control application software, network management system interfaces can also be supplied by RFI to suit individual designs’ operational, interfacing and monitoring requirements.

Off-

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rfi.com.au

SYDNEY (Head Office)Locked Bag 2007Seven Hills NSW 1730Ph: +61 2 8838 0900Fax: +61 2 9630 0844

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© 2015 R F Industries Pty Ltd. Data subject to change without notice.

AN-42325-1

EXAMPLE MULTI-BAND, MULTI-CHANNEL REBROADCAST DESGIN FOR A TWIN-BORE ROAD TUNNEL

Audio Break-In/Message

PA SystemControl panel

Remote Control Room

Supervisory Monitoring & Alarms

Digital I/O E&MAlarm I/O Node

PMCS Interface

RemoteDiagnostics

MessageSelection

Audio break-In/messagePA System Control Panel

Audio break-InVoice Recording

logging Subsystem

AudioShaper/

Processor

MessageInterposing

Player &Recorder

Break-InAudio &Control

Comms Room

Control Room

50 OhmTermination

50 OhmTermination