Two-wire system double-signal transmitting loudspeaker detection control circuit in public broadcasting system

Abstract

Through two-wire system, the control circuit transfers 120V constant voltage audio signal and bi-directional carrier control signal at same time. Being corresponding to own filter, each signal is parallel mixed at output end so as to transfer double signals through two-wire system at same time. Audio transformer at terminal part picks up audio signal. Band pass filter of carrier signal at terminal picks up carrier control signal. Rectifier of carrier signal at terminal picks up DC power source. Fault detection and on / off control for tens to hundreds pieces of speaker can be implemented by terminal process circuit to execute relevant commands. The disclosed two-wire system will replace multiple-wire system thoroughly. Advantages are: low cost, easy to be constructed at site, high efficiency and reliability. The invention is especially suitable to schools, Olympic sports ground and gymnasium, railway stations etc.

Description

Technical field: [0001] The invention relates to a cable public broadcasting transmission line. Specifically, it particularly relates to the simultaneous transmission of constant-pressure audio signals and carrier control signals in two-wire public broadcasting lines, so as to realize fault detection and on / off control of loudspeakers. Background technique: [0002] At present, dozens to hundreds of loudspeakers can be connected to form a broadcast network in a known cable public address system. Generally, two wires are used to transmit 100V or 120V constant voltage audio signal to the speaker. Referred to as two-wire system. However, if the fault detection or on / off control of the loudspeaker is implemented in the broadcasting system, at least two wires should be added to transmit the control signal and power supply, thus forming a four-wire or multi-wire system, in order to realize the fault detection or on / off of the loudspeaker. off control. The disadvantages of usin...

AI Technical Summary

Problems solved by technology

The defect of adopting the multi-wire system is that: (1) in the known multi-wire public address system, two wires for transmitting control signals and DC power are added, which doubles the cable material, which undoubtedly doubles the cost; (2) in the school In larger public address systems such as stadiums, building broadcasting, subway stations, railway stations, and airports, the distance between dozens to hundreds of speakers and the broadcasting equipment can reach hundreds or thousands of meters, and on-site construction must Distinguish between the wires for constant-voltage audio signals and the wires for transmitting control signals, and they cannot be misconnected. This will undoubtedly bring considerable difficulties to on-site construction, and it has not been resolved so far.

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