One, the design requirements of public broadcasting:

The transmission mode: system power output feed mode using wired broadcasting transmission.

The on line attenuation requirements: in the public broadcasting system, from the power device output to the line between the furthest user loudspeaker line attenuation should meet the following requirements:

? service broadcast should not be greater than 2 dB ( 1kHz )

? service broadcast should not be greater than 1 dB ( 1kHz )

Adopts the constant pressure output feeder circuit, the output voltage by 70V or 100V.

The power amplifier capacity calculation method:

The business of broadcasting system and business radio system calculation method: P = K1 * K2 * and Po type : P - power amplifier output total power ( W );

Po--Ki x Pi, each branch at the same time the radio maximum power ( W );

Pi - I shunt user equipment with rated capacity;

Ki - I shunt while demand coefficient;

The service broadcast program at Ki 0.2-0.4, guest room;

Background music Ki 0.7-0.8

K1 - line attenuation compensation coefficient of line attenuation: 1dB 1.26; 2dB 1.58 line attenuation;

K2 - aging coefficient, general 1.2-1.4;

? fire broadcasting system: the system calculation method of calculation method has the following two ways:

A power amplifier according to the capacity of 1.3 times the total number of identified speaker system.

B power amplifier according to the system capacity in a maximum of 3 layer 1.5 times the total number of identified speaker.

Power amplifier with standby

Public broadcasting system should be set up backup power amplifier power amplifier, power amplifier power amplifier at work when a fault occurs can automatically or manually put into use. Important for radio power amplifier ( such as fire emergency broadcasting power amplifier ) standby power amplifier, should be able to work in amplifier failure automatically and immediately put to use. Standby power amplifier quantity should be according to the important radio load capacity determination.

As a speaker set

? in office, living room, locker room 3W loudspeaker box set.

? floor corridor generally adopts ceiling speakers, speaker of the spaced according to the layer ( ceiling height ) is about 2.5 times to consider. Selection of 3-5W ceiling speaker.

?, general meeting room, dining hall, shopping, entertainment and other department to install 3-6W loudspeaker box.

? rooms bedside control panel with 1W-2W speaker.

? in the building decoration and clear height allowed, for large space place should adopt the column or combination sound box.

? in high noise, moist places set speaker, should use the horn loudspeaker. In noise for high places the selected speaker sound pressure level should be higher than the ambient noise in 10-15 dB.

Broadcast system, the power supply requirements

? small capacity of the radio station by the socket of direct power supply; capacity than 500W, set the radio control room, its power supply by the nearest power controller power supply of special railway line.

? AC voltage offset ＆#118alue generally should not be greater than + 10%, when the voltage offset can not meet the limits of equipment requirements, should be in the vicinity of the device with automatic voltage stabilizing device.

? radio AC power supply capacity for the final broadcast equipment AC power consumption capacity of 1.5-2 times.

? fire emergency broadcasting equipment using fire power.

The transmission cable selection

? room service radio line should adopt the copper core cable or copper plastic hinge line.

Other broadcast line? Should adopt the copper plastic hinge line.

? all kinds of program signal lines should be shielded wire.

? fire accident broadcasting line should be used in flame retardant copper core cable or refractory copper core cable.

The route laying mode

The line used to wear? Steel or wire groove laying, and not lighting, power line with wire groove laying.

? fire emergency broadcasting line fire protection measures should be taken.

In two, the emergency broadcast design requirements:

The fire emergency broadcasting loudspeaker settings should meet the following requirements:

? emergency broadcast speaker set in the aisle, halls, restaurants and other public places, the number should be able to guarantee from the floor to a recent speaker of any part of the walking distance of not more than 25 meters. In the aisle at the intersection, the corner should be set speaker. At the end of the last aisle of not more than 12 metres away from the wall. Each power rating of not less than 3W.

? rooms loudspeaker power should not be less than 1W.

? in air conditioning room, ventilation equipment room, laundry room, entertainment venues and garage at the background noise of the loudspeaker, in its broadcast range farthest playback sound pressure level should be higher than the background noise of 15 dB, and to identify the speaker power.

The fire emergency broadcasting feeder voltage should not be greater than 100V. Each floor is set feeder Isolating voltage regulator to ensure that when either the shunt fault, should not affect the other shunt normal radio.

The fire emergency broadcasting output branch should according to the evacuation order control, playing the evacuation instruction floor control procedure is as follows:

? N layer and N layer above the floor of the fire, should be on fire layer is adjacent the upper, lower.

The first layer? Fire, should first put through this layer, 2 layer and underground layer.

? the basement fire, should first connected to each layer and the first floor underground.

The fire accident broadcasting service broadcasts or business radio operable when, should meet the following requirements:

When a fire? Shall be in the fire control room will fire evacuation layer and corresponding amplifier speaker forced into the fire accident broadcast state.

? fire control room should be able to monitor the working state of the fire accident broadcasting amplifier.

Bedside table? Rooms arranged in a loudspeaker, should have the fire broadcasting function.

? if fire accident broadcasting service radio or business radio and loudspeaker is provided with a volume switch, using three wire distribution system should be forced to open fire is broadcast.