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FM Tunnel Broadcast Near-end Transmitter


Specifications:16 channels, 4 optical ports, digital two-way optical fiber technology, wall-mounted

Product introduction:The tunnel broadcast near-end transmitter can digitally process 16 channels of FM broadcast signals; it adopts digital two-way optical fiber technology to monitor and control the working status of each remote unit; all or part of the channels can be switc

ZHC939G FM Tunnel Broadcast Near-end Transmitter

1. Overview

The ZHC939G FM tunnel broadcast near-end transmitter is a front-end device that receives and processes the front-end signal in the tunnel broadcasting system, converts it into an optical signal and transmits it to the remote transmitter of the tunnel. It and the remote transmitter are the main transceiver equipment in the tunnel broadcasting system. They are connected by optical cables. Cooperating with leaky cables or transmitting antennas, it can effectively fill the coverage blind area and extend the coverage of the transmitting station. Mainly used in highway tunnels, underground parking lots, subway tunnels and station halls, civil defense facilities, schools, etc.


2. Features

This transmitter is distinguished from functional modules and can be divided into five parts: FM antenna reception and pre-amplification, FM broadcast signal digital processing unit, electro-optical conversion and optical signal transmission unit, remote monitoring unit, and emergency carrier insertion unit.


l  FM antenna reception pre-amplification: frequency range: 87-108MHz, gain: ≥20dB.

l  FM broadcast signal digital processing digital frequency selection, digital filtering (using FPGA+DDS digital filtering technology.

l  The near-end machine with 4 optical ports can adopt various forms of networking structure, such as chain type, star type, tree type, ring, etc.

l  The wireless link established by the channel 4G router and the monitoring center realize remote monitoring.

l  In an emergency, all 16 output carriers can be used to broadcast emergency interrupt audio.

l  Adopt modular design.

l  The bidirectional optical channel can simultaneously transmit 16 FM carrier frequency signals.

l  Realize remote monitoring.

l  With optical bypass function.

l  This machine is a near-end transmitter in the tunnel broadcast coverage system and must be used in conjunction with a remote transmitter including optical receivers and power amplifiers.


3. Diagram




4. Technical Specifications


Working frequency   band



Carrier number


Channel bandwidth

150KHz, the lowest step   can be set to 100KHz


(AGC off)

Antenna input

42dB±2dB (add LNA)

N type connector



N type connector

Gain adjustment   range and step length

0dB~50dB adjustable, 1dB stepping

Remote/ Near-End

Gain adjustment   error (1dB)





Output power   (maximum)


Multi-carrier   total power

Automatic level   control range


Automatic channel   equalization range


Interrupt   frequency setting range

86108MHz (4 digits after the decimal point)



Frequency   stability


Time delay



Delay compensation

Time delay   compensation range: 125μs

Delay   compensation mode: automatic

Time delay   adjustment accuracy: 1μs

Spurious emission

Spurious emission   in effective working frequency band


Outside the working   frequency band

9kHz~1GHz in band ≤-36dBm

1GHz~12.75GHz in band≤-36dBm




Optical loop function


Optical transceiver alarm function


Number of optical ports

REC support 4 ports

Interface FC/UPC

Optical module rate


Optical module type


Networking function

Star, chain, ring and hybrid networking, etc.

Software upgrade

Support remote   online upgrade, support any node upgrade, support version rollback.

4G router antenna   interface



Operating Voltage

220ACV±20%, 50Hz

Aviation plug

Operating   Temperature


Working   atmosphere


Local and remote   Ethernet RJ45

Can be used for   local and remote communication