The public broadcasting system belongs to a branch of sound amplifying sound system, and the sound amplifying system is also called professional sound system, which involves the edge science of three kinds of subjects, such as electro-acoustic, sound-building and music. Therefore, the final effect of public broadcasting system involves a reasonable and correct electro-acoustic system design and commissioning, good sound communication environment (sound conditions) and accurate on-site tuning three best combination, three complementary indispensable.
Classification of broadcast Systems
The generalized Broadcasting System includes two main categories: sound reinforcement system and acoustic system.
Sound reinforcement system
The speaker and microphone are in the same sound field, and there is howling, distortion and oscillation caused by acoustic feedback and room resonance. To ensure system stability and normal operation, the maximum available system gain is 6dB lower than the critical gain of acoustic feedback self-excited.
The system is only a tape drive, CD-ROM and other sound sources, no microphone, there is no sound feedback, the acoustic feedback coefficient of 0, is a special case of the broadcast system.
The public broadcasting system can be divided into the following categories by use
Outdoor Broadcasting System
Outdoor Broadcasting system is mainly used in stadiums, stations, parks, art squares, music fountains and so on. It is characterized by a large area of service area, broad space. The background noise is large, and the sound transmission is mainly through direct sound; the requirements of high sound pressure, if the surrounding buildings such as reflective objects, the speaker layout is not reasonable, sound waves through multiple reflection and form more than 50ms of delay, will cause double or multiple sound, serious echo and other problems, the impact of sound clarity and audio-visual positioning. The acoustics of outdoor systems are also affected by climatic conditions, wind direction and environmental disturbances.
Indoor Broadcasting System
Indoor Broadcasting System is the most widely used system, including all kinds of theaters, stadiums, dance halls and so on. Its professionalism is very strong, can not only sound, but also for various types of theatrical performance use, the quality of the requirements are very high, the system design not only to consider the electro-acoustic technology, but also involving architectural acoustics. The shape of the room and other factors have a greater impact on the sound quality.
Public Broadcasting System
The public Broadcasting System provides background music and radio programmes for hotels, shopping malls, ports, airports, subways and schools. In recent years, the public broadcasting system is also an emergency broadcast, can be linked with the fire alarm system. The public broadcasting system has more control functions. such as the function of constituency broadcast and full call broadcasting, the function of compulsory power exchange and the priority broadcasting right. The speaker is loaded and distributed and has a long transmission line. In order to reduce transmission line loss, the general use of 70V or 100V fixed voltage high impedance transmission. The sound pressure requirements are not high, the quality of the tenor and medium treble mainly.
With the increase of domestic and international communication, conference call, videoconference and Digital conference system (DCN) have been developing rapidly in recent years. The conference system is widely used in conference centers, hotels, groups and government agencies. The conference system includes the meeting discussion system, the voting system, the simultaneous interpretation system and the videoconference system. Require audio, video (image) system synchronization, all the use of computer control and storage of conference information.
Background music short BGM, is the abbreviation of Back ground music, its main role is to cover up noise and create a relaxed and harmonious atmosphere, listen to people who do not listen attentively, can not distinguish its sound source position, volume is small, is a kind of music to create a relaxed and pleasant atmosphere of the environment. Therefore, the effect of the background music has two, one is psychological cover up the environmental noise, the second is to create the atmosphere with the indoor environment, it is in hotels, hotels, restaurants, shopping malls, hospitals, office buildings and other widely used.