Conference audiovisual system classification
The general sound reinforcement system includes two categories: sound reinforcement system and sound reproducer system:
1. Sound reinforcement system: loudspeaker and speaker in a unified field, there are acoustic feedback and room resonance generated by whistling, distortion and oscillation. In order to ensure that the system is not chaotic and works properly, the maximum available system gain is 6 dB lower than the critical gain for acoustic feedback self-excitation.
2. Resound system: there is only tape drive, optical disc player and other sound sources in the system, there is no speaker, there is no sound feedback possible, the sound feedback coefficient is 0, which belongs to the special case of sound reinforcement system.
Sound reinforcement systems can be divided into the following categories according to their use:
1. Outdoor PA system
Sports venues, stations, parks, art squares, music fountains and other outdoor sound reinforcement systems. It is characterized by large service range, wide space and large background noise. Sound transmission is mainly direct sound; The sound pressure level is high. If there are acoustic reflection objects such as tall buildings nearby, the sound wave will be reflected several times and the sound pressure level will be high, which will cause the sound image positioning difficulty. The acoustics of external systems are also affected by weather conditions, wind direction, environmental disturbances and other factors.
2) Indoor sound system
Among them, the most widely used is the indoor sound reinforcement system, including various cinemas, stadiums, dance halls and so on. Its professionalism is very strong, not only can provide a sound source for various artistic performances, but also has high requirements for sound quality. System design should not only consider electroacoustic technology, but also involve architectural acoustics. Indoor shape and other factors have great influence on sound quality.
3) Event performance system
In addition to the fixed installation system, the PA system also has a mobile system. In a variety of large venues (such as sports venues (gymnasiums), art broadcasting, large banquet halls, etc.) with temporary installation of non-artistic performance of the temporary system called the event performance system. The sound of these activities must be compact, easy to carry, transport and install, high reliability, and can adapt to a variety of harsh use environments. Large-scale activity system investment is large, generally leased to professional audio companies.
4. Conference system
With the increase of domestic and international communication, teleconferencing, video teleconferencing and digital conference system (DCN) have developed rapidly in recent years. The assembly system is widely used in central government, hotels, organizations and government departments.
The conference system mainly includes the conference discussion system, the voting system, the simultaneous interpretation system and the video conference system. This system requires audio, video (image) system synchronization, and computer control, storage.
The design of the compilation and amplification system generally begins with the sound field, and then moves into the power amplifier, the sound processing system, the mixer, and finally the microphone and other sound sources. This gradual backward design step is necessary. Because sound field design is the basis of the function and sound effect of the system, it involves the selection of speakers, sound supply schemes, signal pathways, etc. It is necessary to determine the speaker system to calculate the power amplifier drive power and determine the driver signal path, and then further determine the signal processing scheme and the choice of sound platform according to the distribution scheme of the drive power.
Sound field design is the basis of sound reinforcement system, which involves the final sound effect of the system, but it is often a complicated work. Due to the rapid development of computer technology, acoustic software tools above EASE3.0 can now be used for calculation, and finally meet the desired sound field design speech [1], [2]. In order to achieve the requirements, the sound field design process needs to be repeated several times.
Tape voting or simultaneous interpretation systems can be configured according to different meeting needs.
When voting, delegates simply press the vote button on the device in front of them, and the vote result will be displayed on the LCD screen of the chair machine, or on other screen display devices in the conference room through CCU and DCN software.
Simultaneous speakers usually speak at least 1+3 languages (one mother tongue and three translated languages), with additional seats available when needed, except for official representatives.
Languages can be assigned either wired or wirelessly:
The cable trunk of the DCN system assigns the translation language to the participants. Official delegates listen to the translation language by listening to the headset on the speaker device with the channel selector, and delegates listen to the translation language by listening to the headset with the channel selector
The infrared system is used for wireless transmission in the allocation of radio transmission
A typical infrared system includes infrared transmitters, radiators, and personal infrared receivers:
- Infrared transmitter: Each language channel has a carrier
- Infrared radiator: Used to distribute infrared signals throughout the venue.
It can be inserted into the wall or ceiling during installation. Precise adjustment of radiator installation position can obtain the best field infrared signal cap.
- Infrared receiver: can receive up to 16 language channels, with high-speed conversion channel function, LED display and voice amplification function.