What transmission method is commonly used by public broadcasting systems for transmission?

There are three main transmission methods commonly used in public address systems: audio/wireline constant voltage (fixed resistance) transmission, wireless frequency modulation transmission, and cable FM transmission.

Audio wired constant voltage transmission: The advantage is that the structure is simple, the terminal cost is low, and the stability is particularly strong; the disadvantage is that the wiring is complicated, each terminal must be wired, the equipment should be matched according to power and impedance, the scalability is poor, and the program capacity is small.

Wireless frequency modulation transmission mode: The advantage of this transmission mode is that multiple programs can be played at the same time, and the construction is simple without a large amount of wiring; the disadvantage is that it occupies space frequency resources and is susceptible to low interference stability. Because most public broadcasting or background music systems now integrate emergency fire rescue systems, the stability of wireless FM broadcast transmission methods can cause huge losses in the event of an emergency. Stability is a stumbling block to the development of wireless transmission methods.

The cable FM transmission mode is based on the cable TV coaxial cable frequency division multiplexing technology transmission mode. The advantage of this transmission mode is that it can transmit up to 60 sets of programs at the same time, and the expandability is strong, and the terminal speaker can satisfy the receiving level as long as it is not limited by the amount of power.

Because the cable FM broadcast has a cable transmission with closed-circuit television, it can be used for stereo playback without separate wiring. The number of transmission programs can be extended at any time, and functions such as intelligent broadcast addressable control can be realized. Therefore, this type of transmission is recommended in general use. High cost performance, strong scalability and stable transmission.