Digital audio broadcasting is to encode, modulate and transmit the capitalized sound signal, video signal and various data signal under the digital status. Meanwhile digital broadcasting is a kind of broadcasting technology which is different from AM, FM that we are familiar with. Through the ground launching station, it launches digital signal to achieve the purpose of broadcasting and data information transmission. With technical development, the digital broadcasting transfers not only the traditional audio signal, but also multimedia signals including audio, video, data, character and diagram. 

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Compared With FM and AM, The Digital Broadcasting Has Following Advantages:

Pure sound which can compare favorably with CD;

Strong anti jamming capability, good listening effect;

Suitable for fixed, portable and mobile listening. Good listening effect when quick moving.

Beside the audio program, digital multimedia broadcasting and data service can also be provided. 

In addition, digital broadcasting has other advantages like low transmitting power and full use of transmitting broadband. In recent years, with the rapid development of digital audio transmission technology, digital broadcasting technology has become very mature and attracted more and more attention on its application and development in the field of rail transit. 

Winsion’s broadcasting system has adopted the most advanced digital broadcasting technology in this world. It completely solves the issues existing in traditional simulation broadcasting system including poor sound quality, easy to be disturbed, repeated wiring, complicated maintenance and management and poor interaction performance. The system not only achieves functions including unmanned duty, smart play (including railway announcement, train operation hour, ticketing, station facility instruction, station environment instruction, passenger’s riding and safety reminder and traveling information) but also has got functions like free editing, scene broadcasting. It can intelligently manage broadcasting and receiving of the program by adopting multipath directional addressing technology. By the digital network, it also achieves advanced characters such as fully free system design, audio without any disturbance and other advantages other traditional system can not compare. 

Station passenger transport broadcasting system mainly completes guidance broadcasting of ticket purchasing, waiting, riding and public propaganda. It’s to announce bulletin and provide various audio information to passengers, to organize transport operation and dredge passenger flow and to ensure traffic safety and effective management of passenger transport and service facility. 

Currently the medium-size and small-size railway stations adopts traditional simulation broadcasting but better for large-size and super-huge size stations to use digital broadcasting system. Compare with the simulation broadcasting, the digital broadcasting system based on IP network supports digitalized convertion of different types of simulation sound source. As digital audio broadcasting system, it can apply a mass of audio resource which has been stored in network servers and other carriers with format of data. It has not been restricted to using and transmitting of the simulation signal which are exported from cassette, CD and mic. Moreover, the running platform for digital broadcasting system is the system software. By controlling the network audio steam signal, it’s easy to transmit multi task by any path at the same time, such at functions like video-on-demand, arbitrary point-to-point, arbitrary/unlimited partition, multi task preset. 

Winsion’s IP network-based digital broadcasting system consists of five parts including front end information source equipment, digital signal processing preamp, network audio processing equipment, digital power amplifier, system control and fault detection module and speaker. The system management server controls the working status of all network audio processors of the broadcasting system by Ethernet. Firstly the system send all kinds of information sources to the network audio processor in the control room. The network audio processor will digitalize the input audio and then send it to the network audio processor to be broadcasted in the communication wiring room through the network switch and transmission system under the control of system management server. After the digitalized network transmission of the audio from the control room to the communication wiring room, the network audio processor in the communication wiring room will revert the digital signal to audio signal and send it to relevant power amplifier for broadcasting in relevant area. 

Meanwhile, the system management server transmit the sent control command to all network management controller in the machine room and wiring room through the switch. The network management controller will control switching on/off of relevant equipment of the broadcasting system.

Main Functions of Broadcasting System:

(1)emergency broadcast: In order to make sure the broadcasting can be used under any situation, the machine room and the communication room will be equiped with a set of emergency broadcasting system respectively by the system. The emergency broadcasting uses special audio transmission line to connect directly with the power amplifier in machine room/wiring room, which makes sure the system can still work when abnormal situation occurs.

(2)fire control broadcast: The system has reserved the input interface for fire control broadcasting in the information integration room. When fire or emergency, the broadcasting system will receive the control signal from the fire control broadcasting and automatically cut off what is being broadcasted and change to fire control broadcasting. The fire control broadcast has highest priority.

(3)broadcasting area monitoring: Sometimes the broadcaster need to know the site situation in some broadcasting areas. He/she just need click the monitoring function for relevant broadcasting area on the interface of broadcasting system. The monitoring sampling device of the broadcasting area transmit the broadcasting audio signal in the broadcasting area to the network audio processor in the communication wiring room. After digitalization, it will be transmitted to the network audio processor in the service central control room. The network audio processor in the service central control room will send it to the broadcaster’s operation platform.

(4)cell broadcasting: The digital broadcasting adopts wireless cell broadcasting and connect with the cell broadcasting controller in the machine room/communication wiring room nearby through radio frequency cable by setting wireless communication receiver in entrance hall, exit hall, waiting hall, ticket office, passenger transport duty room and ticket checking/supplement office. When any area needs cell broadcasting, send broadcasting request command to corresponding network management controller, forward to system management server, and the system broadcasting server will decide. If the broadcasting partition for cell broadcasting is not occupied, the broadcasting priority will be lower than priority of the cell broadcasting. The system management server will send command to network management controller immediately. When network management controller receives the command to be broadcasted, the cell broadcasting controller will send the audio signal of the cell broadcasting to the network audio processor. The network audio processor then send it to corresponding power amplifier. Open corresponding broadcasting channel fro site broadcasting.

(5)volume control: The passenger transport broadcasting has already configured volume controller in the VIP room. The staff may adjust the volume of this broadcasting area at site. The volume controller and the speaker in VIP room share the broadcasting partition. An extra audio cable has been connected with the fire control room. When fire occurs, the volume will be adjusted to maximum automatically which is convenient for evacuation at the site.

(6)workload detecting: System has configured workload detectors in the machine room and each communication wiring room. Each workload detector is able to detect the situation of each speaker in 8 broadcasting partitions. The fault of the speaker will be detected in time, which makes maintenance of the sound field more convenient.

(7)noise detection: The system has configured noise detectors at ticket office, waiting room and the platform. Using special noise sensor to detect the environmental noise in the broadcasting area during the interval of broadcasting and adjusting the volume and quality of the speaker dynamically according to the loudness of the environmental noise to maintain the sound of the broadcasting to a certain signal-to-noise ratio.

(8)delayed switch: Because the power amplifier is a kind of device with high power, in order not to affect the equipment due to over current when the broadcasting system gets powered for the first time and all speakers switched on at the same time, the system has configured programmable power supply controller in each broadcasting speaker cabinet. The programmable power supply controller can power up the speakers one by one according to the time set to delay the switching time for speakers.

(9)warm backup design of power amplifier and speaker detection: To ensure the normal operation of the broadcasting system, the system has considered backup of automatic hot switch function of the speaker. The system has configured 1 backup of 4 sets according to the power of broadcasting partition in the machine room and each wiring room. The system has also set power detection controller. It constantly detects input signal and output signal of the power amplifier. When fault occurs to the power amplifier, it will change input audio signal of the power amplifier with fault to the backup speaker. The programmable power supply controller will cut off the power from the power amplifier with fault so that the automatic detection and switch function can be achieved to ensure safe broadcasting without interruption of the broadcasting status.