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You Anhong Public Address System Overview
The public broadcasting system belongs to a branch of the sound reinforcement system, and the sound reinforcement system is also called the professional sound system which involves the edge sciences of electroacoustic, acoustic and musical sounds. Therefore, the final effect of the public broadcasting system involves the design and commissioning of a reasonable and correct electroacoustic system, a sound sound propagation environment (acoustic conditions) and an accurate on-site tuning. The three are mutually complementary and indispensable.
As a system problem, public broadcasting must comprehensively consider the above issues in system design. Based on the well-chosen electro-acoustic equipment, through careful system design, careful system commissioning and sound sounding conditions, we can achieve sound and natural sound effects.
Broadcast system classification:
The broad broadcast system includes two types of sound reinforcement systems and sound playback systems:
1. Sound reinforcement system: The loudspeaker and the microphone are in the same sound field, and there are whistle, distortion and oscillation caused by acoustic feedback and room resonance. To ensure system stability and normal operation, the highest available system gain is 6dB lower than the critical gain for acoustic feedback self-excitation.
2. Sound Reproduction System: There are only sound sources such as tape drives and CD players in the system. There are no microphones, no acoustic feedback is possible, and the acoustic feedback coefficient is 0. This is a special case of the broadcasting system.
Public broadcasting systems can be divided into the following categories according to their purpose
1) Outdoor broadcast system
The outdoor broadcasting system is mainly used for stadiums, stations, parks, art squares, musical fountains, etc. It is characterized by a large service area and a wide space. The background noise is large; the sound propagation is dominated by direct sound; the required sound pressure level is high, if there are reflective objects such as high-rise buildings, the speaker layout is not reasonable, and the sound wave is reflected multiple times and forms a delay of more than 50ms, which may cause Double sound or multiple sounds, serious problems such as echoes, affect the clarity of the sound and sound image positioning. The acoustics of outdoor systems are also affected by weather conditions, wind direction and environmental disturbances.
2) Indoor Broadcasting System
Indoor broadcasting system is the most widely used system, including various theaters, stadiums, dance halls and so on. Its professionalism is very strong. It can be used for non-verbal sound reinforcement and can be used for various artistic performances. It has high requirements for sound quality. System design must not only consider electro-acoustic technology issues, but also involve architectural acoustics. Factors such as the shape of the room have a great influence on the sound quality.
3) Public Broadcasting System
The public broadcasting system provides background music and radio programs for hotels, commercial buildings, ports, airports, subways, and schools. In recent years, the public broadcasting system also serves as an emergency broadcast, which can be linked with a fire alarm system. Public broadcasting systems have more control functions. Such as constituency broadcast and all-call broadcasting functions, mandatory switching functions and priority broadcasting rights functions. Loudspeaker loads are scattered and transmission lines are long. In order to reduce transmission line losses, high-impedance transmission of 70V or 100V constant voltage is generally used. The sound pressure requirement is not high, and the sound quality is mainly midrange and mid-high.
4) Conference System
With the increase of domestic and international exchanges, telephone conferences, video conferences and digital conference systems (DCN) have developed rapidly in recent years. The conference system is widely used in conference centers, hotels, groups and government agencies. The conference system includes a conference discussion system, a voting system, a simultaneous interpretation system and a video conference system. Requires audio and video (image) system synchronization, all use computer control and storage of meeting information.