Knowledge Points to be Considered in the Design of Public Broadcasting System

Transmission mode

The output power of the system is fed by cable broadcasting. Requirements for line attenuation: In public broadcasting systems, line attenuation from the output of public address amplifier equipment to the farthest user speakers on the line should meet the following requirements:
· Service broadcasting should not exceed 2 decibels (1 kHz)
· Service broadcasting should not exceed 1 decibel (1 kHz)

Standby Power Amplifier

The backup power amplifier should be installed in the power amplifier of public address amplifier. The power amplifier can be put into use automatically or manually when the working power amplifier fails. The standby power amplifier of power amplifier for important broadcasting (such as fire accident broadcasting) should be put into use automatically when the working amplifier fails. The number of backup power amplifiers should be determined according to the capacity of important broadcast loads.

Speaker Settings

· Set up 3W speaker box in office, living room, dressing room, etc.
· The roof-suction loudspeaker is usually used in the corridor of the floor. The spacing of the loudspeaker is considered about 2.5 times of the floor height (ceiling height). 3-5W ceiling loudspeaker is selected.
· Lobbies, general meeting rooms, restaurants, shopping malls, entertainment venues and other places should be equipped with 3-6W speaker box.
· The bedside control cabinet in the guest room is equipped with 1W-2W loudspeaker.
· In the case of building decoration and room net height, sound column or combination speaker should be used in large space.
· When loudspeakers are installed in high noise and humid places, horn loudspeakers should be used. The sound pressure level of horn loudspeaker selected in high noise area should be 10-15 dB higher than that of ambient noise.