Combination and characteristics of public broadcasting system

It is understood that the public broadcasting system is now widely used in the market. Whether it is in stores, supermarkets, schools, homes, karaoke halls, gymnasiums, etc., you can hear beautiful singing and information transmission. Indispensable relationship!

1. In civil engineering design, broadcasting systems can be divided into the following categories:

(1) Public broadcasting system for public areas (shopping malls, stations, terminals, shopping malls, restaurants, corridors, classrooms, etc.) and parking lots; this system is mainly used for voice broadcasting, so clarity is paramount. In addition, such a system usually broadcasts background music in peacetime and can be converted into emergency broadcasts in the event of a disaster or emergency.

(2) Broadcast sound system for hotel rooms; this system includes guest room audio broadcasts and emergency broadcasts, which are often broadcasted by bedside tables in rooms. Room broadcasts contain multiple freely selectable bands. During emergency broadcasts, guest rooms The broadcast is automatically interrupted and automatically switched to emergency broadcast.

(3) Hall sound reinforcement systems represented by auditoriums, theaters, and gymnasiums; this is a highly professional sound reinforcement system. It must not only consider electro-acoustic technology issues, but also architectural acoustics issues. Both must be considered in a coordinated manner and must not be discarded. This type of broadcasting system often has comprehensive and multi-purpose requirements. It can not only be used for venue language reinforcement, but also often used for cultural performances. For large-scale live performance sound systems, the electric power is low There are tens of thousands, and hundreds of thousands of watts. Therefore, it is necessary to use high-power speakers and power amplifiers, and there are certain requirements in the system configuration and equipment selection. At the same time, attention should be paid to the load of the power lines.

(4) Broadcast sound systems for conference rooms, lecture halls, etc. These systems are also generally set up as a background music and emergency broadcast system provided by public broadcasting, but are also often used in conference rooms and lecture halls due to their special characteristics. Set up a conference broadcast system separately. For more demanding or international conference halls, special audio-visual systems such as simultaneous interpretation systems, conference voting systems and large-screen projection televisions need to be designed separately.

As can be seen from the introduction above, the broadcasting sound systems for various buildings, hotels, and other civil buildings can basically be classified into three types: one is the Public Address System (PublicAddresssystem, referred to as PA), which is a cable broadcasting system, which includes the background Music and emergency broadcast functions are usually combined together, and usually play background music or other programs. In the event of an emergency such as a fire, it is converted into an alarm broadcast. In this system, the microphone for broadcasting and the speaker for broadcasting to the public are generally not in the same room, so there is no problem of silent feedback, and it is a typical system of constant pressure transmission. The second is the hall sound reinforcement system. This system uses Professional audio equipment requires high-powered speaker systems and amplifiers. Because microphones and loudspeakers are located in the same hall, there are problems of acoustic feedback and howling, and because of their short distance, the system is generally used Low-resistance direct transmission method; Third, the conference system used in the specialty store. Although it is also a sound reinforcement system, it has its special requirements, such as a sound interpretation system.

2. Composition of public broadcasting sound system

No matter what kind of broadcasting sound system, it can be basically divided into four parts: program source equipment, signal amplification and processing equipment, transmission lines and speaker systems.

â—† Program source equipment: Program sources are usually provided for radio broadcasting, laser record players and recording decks, in addition to microphones and electronic musical instruments.

â—† Signal amplification and processing equipment: including mixers, preamps, power amplifiers and various controllers and audio processing equipment. The primary task of this part of the equipment is signal amplification, followed by signal selection. Mixers and preamps have similar functions and status (of course, the functions and performance indicators of mixers are higher). Their basic function is to complete signal selection and preamplification. In addition, they also carry out various adjustments of volume and sound effects. And control. Sometimes for better frequency equalization and timbre beautification, an equalizer is also separately invested. This part is the "control center" of the entire broadcasting sound system. The power amplifier amplifies the signal sent by the preamplifier or the mixer, and then pushes the speaker through the transmission line.

â—† Although the transmission line is simple, it has different requirements with different systems and transmission methods. For auditoriums, theaters, etc., because the distance between the power amplifier and the speaker is not far, a direct feed method with low resistance and large current is generally used, and the transmission line requires a dedicated speaker cable. The losses caused by transmission lines often use high-voltage transmission methods. Because the transmission current is small, the transmission lines are not required.

â—† Speaker system: The speaker system requires the entire system to be matched, and the choice of its location should also be realistic. Auditoriums, theaters, and dance halls have high requirements for sound quality and sound quality, and speakers generally use high-power speakers; and public broadcasting systems, because of their low sound requirements, generally use 3W-6W ceiling speakers.

3. Characteristics of public broadcasting system

The public broadcasting system's main function is to mask the noise and create a relaxed and harmonious atmosphere. If the listener does not concentrate on listening, he cannot discern its sound source position. The volume is low, which is a kind of atmosphere that can create a relaxed and pleasant environment. music.

Therefore, there are two effects of public broadcasting. One is to cover up the environmental noise psychologically, and the other is to create an atmosphere suitable for the indoor environment. It is widely used in hotels, hotels, restaurants, shopping malls, hospitals, office buildings and so on. The music should be lyrical or light-hearted, and strongly irritating music is not suitable.

Public broadcasting is not stereo, but mono music. This is because stereo requires to be able to distinguish the direction of the sound source and have a sense of depth, while background music is not aware of where the sound comes from, and does not want to. The location of the sound source is felt for others, and it is required to hide the sound source, and the volume should be relatively low, and the principle of not affecting the two people speaking to each other is the principle.

4. Features of the fire broadcast function

Fire broadcasting is activated when an accident occurs (so it is closely related to personal safety). Fire broadcasting has the following characteristics:

â—† The fire alarm signal should have high priority in the system, and it can have the function of cutting off the background music and calling for someone.

â—† It should be easy for fire alarm staff to operate;

â—† Transmission cables and speakers should have fire protection characteristics;

â—† Allow the implementation of alarm broadcasting in case of AC power failure.

General sequence of public broadcasting engineering design

The public broadcasting mentioned here refers to the sound broadcasting of cable transmission, which is usually used in shopping malls, public venues, buildings, and communities, and is used for background music broadcasting, paging broadcasting, and catastrophic broadcasts forcibly inserted. The design of this type of public broadcasting project is usually carried out in the following order:

1. The selection and configuration of broadcast speakers should be considered first.

2. The selection of broadcasting power amplifier.

3. Broadcast partition.