ubway broadcasting system is a special subsystem of subway communication system, which plays a very important role in the organization of subway operation, passenger service, disaster prevention and rescue, equipment maintenance and so on. In normal times, the different areas of the subway station for ticket, check-in, arrival, waiting for the bus, bus, departure, transfer and other services to broadcast different terms of service and matters needing attention, to provide various information services. To maintain the station order and effectively guide passengers to get off and on the train, thus creating conditions to shorten the stopping time of the train station and ensure that the train is on time. Provide operation broadcasting services such as safety warning and notification for dispatching and command, car dispatching, vehicle debugging, equipment maintenance, line maintenance, power supply rail delivery and equipment delivery and power failure in metro operation areas such as the depot and tunnel section of the depot; When the subway passenger flow surges due to major activities and festivals, it serves as an important means to implement the emergency passenger transport organization and provide guarantee for the operation organization of large passenger flow: it serves as an important tool for emergency transport and rescue. The broadcasting system provides advanced working tools for metro passenger transport, driving, disaster prevention and equipment maintenance. Improved the subway passenger service quality and the ability to deal with emergencies f.
1 system structure
1. 1 broadcasting system
Topology diagram of broadcast system,
1. The control center
The subway broadcasting system adopts the current mainstream control center and station control structure. The control center is connected to the station via a network. The command and audio of the control center are transmitted to the station through the network. The broadcasting system is equipped with network management computer in the control center, which can measure and control the whole system.
1. Station broadcast system
Topology diagram,
The subway broadcasting system is a modern advanced broadcasting system, mainly including sound source, sound source management control equipment, power amplifier, output control equipment, sound reduction equipment and power management equipment.
Station broadcasting system adopts bus structure, module/board form equipment design. All modules/boards can be replaced online. It has the advantages of flexible configuration, convenient maintenance and good expansibility. All the modules and equipment in the station broadcasting system are connected to the internal TBA bus, and the bus resources are coordinated and managed by the central control module. When the operator carries out the related operation in the man-machine interface, the central controller will coordinate all the function modules of the broadcasting system to complete the broadcasting function.
There are many ways for front-end source input, including microphone live broadcast, pre-recorded voice end broadcast, line broadcast and so on. It is also able to broadcast audio from other systems to the target broadcast area.
1. 3 center broadcasting system center
Broadcast system topology.
The central broadcasting system can complete the selection of all stations. To broadcast or listen to. At present, the control interface of broadcast system is mainly integrated by integrated monitoring system. Complete the function implementation by interfacing with each other.
1. Car depot and parking lot broadcast system
The depot and parking lot broadcast system structure is the same as the station, because the broadcast division is less, the corresponding equipment quantity also reduces. Control center broadcast system to the car depot, car park broadcast system network management only, not broadcast operations.
2 system functions
1) central broadcasting function. Control center operators are able to broadcast the station and field under their jurisdiction.
2) central monitoring function. The operator of the control center can listen to the broadcast content of each station broadcasting area.
3) emergency broadcasting function. Emergency broadcast control module is configured in the broadcast system. When the system equipment fails, the emergency broadcast button of disaster prevention broadcast control box can be pressed for emergency broadcast.
4) automatic inbound broadcast. The broadcasting system receives the information sent by the signal system. When the train is about to arrive, arrive and leave the station, the pre-stored speech content in the digital speech synthesis module will be activated for automatic broadcasting.
5) live broadcast (microphone). Live broadcast system through the microphone real-time pick up operator's mouth broadcast audio real-time broadcast to the target broadcast area.
6) background music. Background music is accessed to the system through the player as a separate audio channel. Background music conceals environmental noise and creates an atmosphere suitable for virtual environment in the station.
7) pre-recorded broadcasts. A digital speech synthesis module is configured at the station. Store and play audio in digital format
8) monitoring function. The broadcasting system is set with monitoring equipment, with permission to monitor the contents of each broadcast under its jurisdiction, and the listening volume can be adjusted.
9) parallel broadcast function. The audio matrix module is set in the system. Different source input can be connected to non-broadcast input at the same time... Without interference, the function of parallel broadcasting can be realized
10) priority broadcast function. The system has priority rating broadcast function. The operations of target broadcast overlay and conflict are coordinated according to the unassigned priority.
11) the power amplifier's state can be detected in real time by the power amplifier's function broadcasting system, which detects the power amplifier's state through the power amplifier's fault door movement detection and automatic switch. When the power amplifier fails, it will be automatically switched to the standby power amplifier and replace the fault power amplifier to ensure the continuous effectiveness of the broadcasting process.
12) radio volume is automatically adjusted. The broadcasting system detects the noise through the sensor installed on the platform, and automatically adjusts the volume of the broadcasting domain according to the detected noise value, so as to maintain a certain signal-to-noise ratio.
13) automatic broadcast release. After some broadcast operation is completed, the broadcast system will automatically release the broadcast area according to the preset way of the program. Avoid invalid occupation of the area
14) power on in time sequence. In order to protect the loudspeaker and power supply from the power amplifier's starting current, the broadcasting system controls the power amplifier by the time sequence
15) load protection. The system can detect the load state through the sampling of internal equipment and the software algorithm. Disconnect the load as necessary. Cut off the fault extension path.
16) circular broadcast. By default, the broadcast system will play the specific numbered speech segments in the speech synthesis module in a loop.
17) broadcast predictor function. All broadcast operations except emergency broadcasting will start with a prompt tone to remind the audience to pay attention.
18) recording function. The recording module of the broadcasting system can record the broadcast content. The recording content can be inquired according to the number and the recording content cannot be erased and recorded in a circular way.
19) network management function. The network management terminal can monitor and manage all broadcast equipment, and has the function of centralized maintenance and self-diagnosis. Fault management, performance management, configuration management, security management. Real - time monitoring center, station, depot broadcast equipment operation status. Tunnel and underground works.
3 interface
The interface scheme of broadcast system is flexible and diversified, and the available ways include I/O ten contacts, RS 1 422, Ethernet and other means to connect with the system such as comprehensive monitoring, telephone, wireless, centralized alarm, FAS, etc., to introduce necessary audio into the broadcast system, which facilitates the field and station management of operators
4 equipment selection
4. 1 choice of speakers
The public broadcasting system loudspeaker should be selected according to the environment with different specifications. If: be in the indoor of ceiling condole top, appropriate USES built-in smallpox loudspeaker, can be equipped with fireproof cover when necessary. The indoor that has frame condole only top, appropriate USES condole to install type canister type speaker box or the smallpox loudspeaker that has rear cover. The indoor that does not have condole top, criterion appropriate chooses wall to hang type loudspeaker or indoor sound column. Outside, it is advisable to use the sound column or horn outside.
The public broadcasting system loudspeaker is configured in the broadcast system on the principle of uniformity and dispersion. The degree of dispersion should ensure that the signal-to-noise ratio in the broadcast is not less than 15 dB. Generally in addition to the bustling place. Roughly consider background noise as 65 ~ 70 dB. Therefore, the sound pressure level of broadcast should be above 80~85 dB.
In the approximate calculation, the sound pressure level SPL covered by the speaker has the following relations with the sensitivity SPKdB of the speaker, the power P of the feed speaker, and the distance r between the listening point and the speaker: SPL=SPKdB+101gP - 20lgr
From this approximation calculation, the ceiling is not higher than 3m in the stadium. The top loudspeaker can be roughly 5 ~ 8 m away from each other evenly configured. In addition, in the JGJ 16-2008 electrical design code for civil buildings, there are some hard and fast rules on cable broadcasting and fire accident broadcasting design and installation: "public places such as walkways, halls, restaurants, etc., the number of loudspeaker configurations should ensure that the walking distance from any part of this floor to the nearest loudspeaker should not exceed 15m. Loudspeaker should be installed at the intersection and turning of the aisle. The distance of the last speaker should be no more than 8 m"
4. 2. Power amplifier selection
One of the main features of the amplifier chosen for public broadcasting system is the constant voltage output, which is due to the fact that the broadcast circuit is usually quite long and the high voltage transmission reduces the loss on the circuit. The rated power of the broadcast amplifier depends on the total power of the loudspeaker.
The broadcasting system takes into account such factors as line loss and aging. The rated output power of the amplifier is calculated as follows: Po=KlxK2xK3xKnxP1xP2xP3
Where Po: represents the electrical power and;
P1 is the compensation coefficient of line loss, taking 1. 26 ~ 1. 58.
P2 is the aging coefficient, taking 1. 2 ~ l_4;
P3 is the field demand coefficient, and the background music system takes 0. 5 to 0. 6. Business broadcast is 0. 7 ~ 0. 8, fire accident broadcast 1. 0.
Sinusoidal electronic's unique high-efficiency class d-class non-output transformer power amplifier technology supports the power amplifier array from 100w-3kw, integrates automatic power amplifier backup switcher, and is light in weight, high in efficiency and small in volume.
4. 3 selection of speaker connection cable
The public address system USES twin sheaths to broadcast cables. This can effectively overcome the effect of stray capacitance between lines. At the same time, the outer layer of the cable is wrapped with a plastic coat, which can protect the internal twisted wire and avoid the cut of line groove, bridge frame and short circuit inner core wire during the construction process.
Considering the cost performance, the broadcast transmission cable specification can be selected according to table 1
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