【 Weak current College 】 public radio broadcasting systems-fire protection

Broadcast audio systems range from factories, schools, hotels, stations, terminals, the square to the venue, theater, Stadium, residential district, are closely associated with it.
In the civil construction design, the broadcasting system can be divided into the following categories:
Public area (square, station, dock, shopping malls, restaurants, corridors, rooms, etc.) and parking lots of the public broadcasting system. This system is mainly used for voice broadcast, so the sharpness is first and foremost. Moreover, such systems are usually conducted background music broadcasting, in the event of a disaster or emergency situations, and can be converted to an emergency broadcast.
Facing the hotel room of radio audio system. This system includes room audio broadcasting and emergency broadcast, often located in room of radio broadcasting, room bedside cabinet contains more than one can be freely chosen by the band, in the emergency broadcast, the rooms shall be automatically interrupted the broadcast, and automatically switch to the emergency broadcast.
To Hall, theater, Stadium, represented by auditoria system. This is the professional sound reinforcement system strong, not only to consider the issue, but also audio engineering Architectural Acoustics issues involved. Both are to be integrated, driveway, such broadcasting system often have integrated multi-application requirements, not only for sound reinforcement, the venue is also commonly used in theatrical performances, etc., for large on-site performance sound system, electric power from a few tens of thousands, many hundreds of Watts, the use of high-power speakers and amplifier, system configuration and equipment selection, there are certain requirements, at the same time it should be noted that the load on the power lines.
Conference room, Auditorium, oriented broadcast sound system. Such systems typically is set to public broadcasting provided background music and emergency broadcasting system of dual-use, but because of their special nature so often in the Conference room and Auditorium separate set meeting the broadcasting system. For more demanding or International Conference Hall, also need to be designed such as simultaneous interpretation system, meeting voting system, as well as large-screen projection television special audio-visual system.
From the above, for a variety of buildings, hotels and other residential buildings of broadcasting sound system, basically can be categorised into three types:
First, the public broadcasting system, the social system, it includes cable broadcasting background music and emergency broadcasting features, typically, usually play background music or other programs, fire and other emergencies, converted to alarm broadcast. This system of broadcasting with microphone and speakers to public broadcasting are generally not at the same room, so silent feedback issues, and to the constant pressure-transmission mode for its typical system;
Second, auditoria system, this system uses professional audio equipment, and requires a high-power speaker system and power amplifier, microphone and sound reinforcement with speakers with a Hall, there exists sound feedback and Whistler, and because of the distance is shorter, so the system generally use low resistance direct transmission; third, a dedicated conference system, it is also an amplification system, but with their special requirements, such as simultaneous interpretation system, etc.
Broadcast audio system composed of
No matter what kind of broadcasting sound system, its basic can be divided into four sections: shows devices, signal amplification and processing equipment, transmission lines and speaker system. Program source: program source is typically a radio, CD player and recorder deck and other equipment to provide, in addition to the microphone, electronic musical instruments, etc.
Signal amplification and handling equipment: including sound mixer, preamplifier, power amplifier and a variety of controller and audio processing devices. This part of the device's first task is to signal amplification, the second is the signal selection, sound mixer and preamplifier role and status of similar (and of course a mixer functionality and performance indicators higher), their basic function is to complete the signal pre-amplification of choice and, in addition to taking on the volume and sound effects for various adjustment and control. Sometimes in order to better frequency balance and tone beautification, also separately into the graphic equalizer. This part is the entire broadcast sound system of the "control center".
Power amplifier the preamplifier or mixer sent signals power zoom, and then through the transmission lines to promote speakers reproducing. Transmission line is simple, but as the system and the transmission mode of different and have different requirements on Hall, theatre, etc., due to the power amplifier and speaker distance, generally use low resistance and high current direct feed, transmission line requires a dedicated speaker cables, and the public broadcasting system, as the service area, long distance, in order to reduce the losses caused by the transmission lines, often using high pressure transmission, transmission current small, less demanding on the transmission line.
Loudspeaker: the loudspeaker system requires that the entire system to match, at the same time the choice of its location but also realistic. Hall, theatre, singing tone, quality requirements, and the speaker generally uses high-power speaker; the public broadcasting system, because it is not required on the tone is so high, generally used the good 3W-6W ceiling loudspeaker;
Broadcasting system features:
Short for BCM, background music is an abbreviation, it BACKGROUDMUSIC's main role is to mask the noise and to create a harmonious atmosphere in a relaxed, to hear if anyone does not listen, you will not be ableto identify its source location, the volume is small, is a way to create a relaxed atmosphere of the music. Therefore, the background music of effect has two, one is psychologically cover environmental noise, the second is to create and adapt the indoor environment, an atmosphere of its hotels, hotels, restaurants, shopping malls, hospitals, office buildings etc. Music should be lyrical style or relaxed strongly stress of music is not appropriate.
The background music is not a stereo, mono music, this is because stereo requirements can distinguish any noise source azimuth, and have a sense of depth and background music are not listen to that doesn't realize voice where to, and do not want to feel any noise source location, and request that the source of subtle, and volume to lighter, without affecting the two opposite speech as principle.
Fire broadcasting function characteristics: fire broadcasting is enabled when the accident occurred, therefore it with personal security are closely related.
Thus fire broadcasting has the following characteristics:
Fire alarm signal should be in the system has the highest priority on the backgroundMusic and call someone has shut-off function, such as State. Should be made to fire alarm watch operation. Transmission cable and loudspeaker with fire characteristics. In case of AC power to guarantee implementation of alarm broadcast.
1, public broadcasting engineering design of the General order of the public broadcasting refers to the cable transmission of a sound broadcast, usually for public places, buildings, community, for background music radio, paging, broadcasting and forced into the disastrous broadcast use.
This kind of public broadcasting engineering design, usually the following order:
First of all should be considered broadcasting for selection, configuration of the speakers, the choice of radio power amplifier, radio Division.
2, radio speakers selection and configuration
Selection of the radio speakers: in principle should be considered as environmental selection of different varieties and specifications of the radio speakers. For example, in a ceiling, ceiling-mounted indoor, use embedded, not the back cover of the ceiling speakers. If CH-705 series. The speakers structure simple, relatively cheap and easy construction. The main disadvantage is that there is no back cover, susceptible to insects and rodents bite.
The only frame ceiling without ceiling Interior (such as the u.s. market), expressing the hoisting-and-tube-type box (ST-708S) or back cover of the ceiling speakers (such as XT-701N ~ 705 series). Since the ceiling is equivalent to an infinite baffle, self-love a ceiling under the conditions of use without the back cover of the speakers also does not cause sound short circuit. And when the situation without ceiling, if you still use no speakers back cover of smallpox, the effect is very poor. Then, in principle, the use of lifting and speakers. However, if such investment is large, you can also use the back cover of the ceiling speakers. Have the back cover of the back cover of ceiling speakers not only general mechanical protection and, to a certain extent, to prevent the role of sound circuit.
In ceiling-mounted indoor (such as the underground car park), to choose wall-mounted speakers or indoor sound columns. The former as BG-105, BG-106, BG-108 series, the latter as SN-302 ~ 304 series.
Outdoors, use outdoor sound columns or horn. The former as SY-510 ~ 540, SY-611 ~ 616 series: the latter as HS-30Q ~ 150Q series. This type of code string and Horn is not only waterproof function and the volume is large, spacious outdoor environment, no reverberation effect, select the volume for a large variety is necessary.
In the garden, lawn, use grass speakers. If S-601 ~ S-1001, KT-620, 28A, DT-21A ~. This type of speaker waterproof, beautiful, and the volume and audio quality are very high.
The decoration is fastidious, ceiling high wide Hall, use elegant, tonal harmony of hoisting-and-speakers, such as the series, set fire to ST-708S demanding situations, use set of speakers. For example ST-708S series. These speakers are sealed type, its outlet port matching with flame retardant casing.
3, radio speaker configuration
Radio speakers, in principle, to the principle of uniform, dispersed in broadcasting service area, the degree of its dispersion should guarantee the service area of signal to noise ratio is not less than 15DB. Typically, advanced Office noise floor of the corridor is about 48 ~ 52DB, supermarket of the noise floor, approximately 58 ~ 63DB downtown section of background noise is approximately 70 ~ 75DB. Considering that in the event of an accident, the site may be confusing, so the need for emergency broadcasting, even if the broadcast service area is the Office, and do not put the background noise estimation too low. Made sure of this, as a general consideration, in addition to the bustling lively places, it may be more or less the background noise as 65 ~ 70DB (except for special circumstances). According to this projection, radio coverage of the sound pressure level to more than 80 ~ 85DB.
In view of the radio speakers are usually distributed configuration, the broadcast coverage of the sound pressure level can be approximated as a single radio speakers. According to the theory of electro-acoustics, speaker covering area of the sound pressure level of sensitivity SPL with speakers-LM, fed to speakers power P, listening points and speaker distance R, the following relationship:
SPL=LM+10LgP-20Lgrdb（1）
Ceiling speaker sensitivity level in 88 ~ 93DB: rated power: 3 ~ 10W. To 90DB/8W, BM in the speakers sound pressure level at approximately 81DB. The above calculation does not consider early reflections group contributions. Indoors, the early reflections and the adjacent speakers contribution will enable the sound pressure level increase of about 2 ~ 3DB.
The approximate calculation based on the above, the ceiling is not higher than 3 m venue, ceiling speakers generally can mutual distance 5 ~ 8M uniform configuration. If you only consider background music regardless of the emergency broadcast, you can increase the distance to 8 ~ 12M. In addition, applicable to the Chinese mainland's fire radio design installation specification (hereinafter referred to as "specifications:) there are some mandatory:" corridors, halls, restaurants and public places, speaker configuration number, should be able to guarantee that any part of this layer to the last speaker walking distance not exceeding 15M. The intersection in the aisle, the corner should set speakers. Aisle at the end of the last speaker distance from wall is not greater than 8M ".
There was virtually no outdoor places early reflections group, a single radio speakers effective coverage can only take the floor above calculations. Due to the lower bound of the corresponding distance is short, so in principle should be used by multiple speakers consisting of allweather. Fed to speakers groups (for example allweather) signal power each doubled (provided that the group could accept), sound pressure level can enhance 3DB. Please note that the "double" meaning. From 1 to 2 is double and critical increase by 2 is doubled. In addition, the distance each doubles, sound pressure level decreases 6DB. According to the above-mentioned rules is not difficult to project the outdoor sound column configuration. For example, to CS-540 outdoor sound columns, for example, its rated power 40W, is a single ceiling speakers of more than 4 times. Therefore, the effective distance covered is greater than a single ceiling speakers 2 x. In fact, this distance can also be larger. Because the sound column of sensitivity than singleA ceiling speakers to high (about 3 ~ 6DB), while each additional point DB, distance can be doubled. That is the 540 allweather can be up to the distance covered, but the code above 20M column comparison of radiation angle in its narrow, just in front of about 60 ~ 90 ° (horizontal) or so effective. The specific calculation available-(1).
Radio power amplifier selection radio power amplifier is different from the HI-FI amplifier, its main feature is a 70V and 100V voltage output terminal, this is because the broadcasting channels are usually fairly long, high-voltage transmission line loss can be reduced. Radio power amplifier of the most important parameter is the rated output power, should use the rated output power, subject to the total power of the radio speakers.
The broadcasting system, as long as broadcast speaker power less than or equal to the amplifier's rated power and voltage parameters are the same, you can feel free to adapt, but considering the line loss, aging and other factors, should be appropriate to leave power. According to the "standard" requirements, PA equipment capacity (corresponding to the rated output power) should normally be calculated according to the following type:
P=K1.K2.P0∑(2)
P--amplifier device output total power (W) P0--each tap (equivalent to partition) at maximum power when broadcasting P0 = KI-PIPI--the I partition speakers rated capacity KI--the I partition at the same time need to factor in the service broadcast room programs, take 0.2 ~ 0.4 background music system, take 0.5 ~ 0.6 business of broadcasting, 0.7 ~ 0.8 fire broadcasting, 1.0K1--line attenuation compensation coefficient: 1.26 ~ 1.58K2--aging coefficient: 1.2 ~ 1.4 accordingly, if that is the background music system, broadcasting amplifier's rated output power shall be broadcast speaker total power of 1.3 times.
However, all of the public broadcasting system in principle should be can't casualty emergency broadcast. Therefore, the system shall be provided with emergency radio power amplifier. According to the "standard" requirements, emergency broadcasting amplifier's rated output power shall be broadcast speaker largest three partitions in the speakers volume totals 1.5 times broadcasting partition a public broadcasting system is often divided into several zones, from the management (or pre-programming) decide which area shall publish broadcast, those regions to suspend the broadcasts, the region shall insert the emergency broadcast, etc.
In principle, the partition scheme depends on the customer's needs. Usually refer to the following rules:
1. building usually to floor area, shopping centre, playground, usually to sector partition, stadiums usually stand partition, residential, resort, usually by property management Division, and so on.
2. Management and public places should be located.
3. important departments or broadcast speaker tone King necessary adjusted by on-site staff of separate communities. In General, the partitioning is designed for easy management. Anyone who needs to be treated separately in part, should be split or a different area. However, each region, the total power of the radio speakers should not be too large, with partitions and amplifier's capacity to adapt to SYB series PAS-2013D partition manager, for example, each region's power capacity to 500VA, but 10 districts should not exceed capacity 1000VA, accordingly, if the 10 districts full load operation, the average area should not exceed 100VA (approx. 100W).
Community public broadcasting system structure housing community public broadcasting system structure consists of four parts:
Radio power amplifier, audio sources in/out, reproducing equipment, intelligent play. 4 persons for organic seamless integration of a unified public broadcasting system. The structure's design takes fully into account the needs of the community features, and focus on the construction costs of the system.