Bus system five-party intercom system

The utility model discloses a bus system five-party intercom system, which comprises a machine room handle machine, a car roof interphone, a pit interphone, a car interphone, a duty room host, a decoder and a system power supply, and is characterized in that the car roof interphone, the pit interphone, the car interphone, the duty room host and the decoder are respectively in communication connection with the machine room handle machine through communication lines; the elevator car interphone comprises a microphone amplifier, an audio power amplification circuit for a loudspeaker, a transmitting attenuator, a receiving attenuator, a background noise level detection system and an attenuator control system, the power amplification circuit realizes local voice transmission, and a decoder is a universal phase-locked loop circuit tone decoder. According to the utility model, a cable is connected to a decoder to form a subsystem, and finally the subsystem and a duty room host are connected through a four-core bus t