Provided is a communication system for an air conditioner including a housing and a control board accommodated in the housing. The communication system includes: a communication conversion unit accommodated in the housing and configured to acquire a required electric signal from the control board and to convert the electric signal into a digital signal for wire transmission; a cable having a first end connected to the communication conversion unit, the cable being drawn out of the housing to outside; and an antenna unit connected to a second end of the cable located outside the housing, the antenna unit being configured to establish wireless communication with a base station.

A signal transmission circuit includes a common frequency filter configured to filter a signal centering on a common frequency that is an anti-resonance frequency; a first frequency filter configured to filter a signal centering on a first frequency that is an anti-resonance frequency; a second frequency filter configured to filter a signal centering on a second frequency that is an anti-resonance frequency; a first route connected to a first signal wiring line configured to transmit a digital signal; and a second route connected to a second signal wiring line configured to transmit a digital signal. The first route has the common frequency filter connected to a power supply circuit, and the first frequency filter disposed between the common frequency filter and the first signal wiring line and connected in series to the common frequency filter, the second route has the common frequency filter, and the second frequency filter disposed between the common frequency filter and the second signal wiring line and connected in series to the common frequency filter, and both the first frequency and the second frequency are equal to or higher than the common frequency.

A signal transmission circuit includes a common frequency filter configured to filter a signal centering on a common frequency that is an anti-resonance frequency; a first frequency filter configured to filter a signal centering on a first frequency that is an anti-resonance frequency; a second frequency filter configured to filter a signal centering on a second frequency that is an anti-resonance frequency; a first route connected to a first signal wiring line configured to transmit a digital signal; and a second route connected to a second signal wiring line configured to transmit a digital signal. The first route has the common frequency filter connected to a power supply circuit, and the first frequency filter disposed between the common frequency filter and the first signal wiring line and connected in series to the common frequency filter, the second route has the common frequency filter, and the second frequency filter disposed between the common frequency filter and the second signal wiring line and connected in series to the common frequency filter, and both the first frequency and the second frequency are equal to or higher than the common frequency.

An air conditioner current loop communication circuit includes an indoor unit current loop communication circuit and an outdoor unit current loop communication circuit connected to each other via a communication connection wire and an AC power connection wire to form a current loop communication loop, an indoor microcontroller unit (MCU) and an outdoor MCU configured to communicate with each other through the current loop communication loop, and a switching power supply circuit connected in series to the communication connection wire or the AC power connection wire and configured to output a DC power to the current loop communication loop.

An air conditioner current loop communication circuit includes an indoor unit current loop communication circuit and an outdoor unit current loop communication circuit connected to each other via a communication connection wire and an AC power connection wire to form a current loop communication loop, an indoor microcontroller unit (MCU) and an outdoor MCU configured to communicate with each other through the current loop communication loop, and a switching power supply circuit connected in series to the communication connection wire or the AC power connection wire and configured to output a DC power to the current loop communication loop.

A head-end equipment associated with a communication system configured to interface with an interference group (IG) composed of two or more modems is disclosed. The head-end equipment comprises a memory configured to store a plurality of instructions; and one or more processors configured to retrieve the plurality of instructions from the memory. In some embodiments, the one or more processors, upon execution of the plurality of instructions from the memory, is configured to generate an advanced warning signal to be provided to one or more modems associated with the IG. In some embodiments, the advanced warning signal comprises an information that a select modem, different from the one or more modems, in the IG will be initiating an upstream communication in a select frequency band, as well as information on a start time and a duration of the upstream communication.

A head-end equipment associated with a communication system configured to interface with an interference group (IG) composed of two or more modems is disclosed. The head-end equipment comprises a memory configured to store a plurality of instructions; and one or more processors configured to retrieve the plurality of instructions from the memory. In some embodiments, the one or more processors, upon execution of the plurality of instructions from the memory, is configured to generate an advanced warning signal to be provided to one or more modems associated with the IG. In some embodiments, the advanced warning signal comprises an information that a select modem, different from the one or more modems, in the IG will be initiating an upstream communication in a select frequency band, as well as information on a start time and a duration of the upstream communication.

A master module (52A) mediates communication between an electric apparatus (6) to which a signal processing device (100) is connected and apparatus control devices (3, 4B) that control the electric apparatus. The master module is provided with: a plurality of first communication ports (54) for respectively connecting to a plurality of signal processing devices via a communication cable (51) for transmitting a superimposed signal; a data signal processing unit (44) that extracts a data signal from the superimposed signal received through the first communication port; an abnormality information generation unit (504) that, on the basis of status information that is included in the extracted data signal and indicates an abnormal state of the electric apparatus, generates abnormality information which indicates information related to an abnormality that has occurred; and an information output unit (503) that outputs the abnormality information such that the apparatus control devices can acquire the abnormality information.

A master module (52A) mediates communication between an electric apparatus (6) to which a signal processing device (100) is connected and apparatus control devices (3, 4B) that control the electric apparatus. The master module is provided with: a plurality of first communication ports (54) for respectively connecting to a plurality of signal processing devices via a communication cable (51) for transmitting a superimposed signal; a data signal processing unit (44) that extracts a data signal from the superimposed signal received through the first communication port; an abnormality information generation unit (504) that, on the basis of status information that is included in the extracted data signal and indicates an abnormal state of the electric apparatus, generates abnormality information which indicates information related to an abnormality that has occurred; and an information output unit (503) that outputs the abnormality information such that the apparatus control devices can acquire the abnormality information.

The disclosure relates to a communications system having a transmitter and receiver connected via a transmission line. An example communications receiver (202) comprises: a pair of input connections (211, 212) for connecting to a transmission line (203); a termination resistance (213) equal to a characteristic impedance (Zc) of the transmission line (203); an air core transformer (205) having an input coil (206) connected to the pair of input connections (211, 212) via the termination resistance (213); and a comparator circuit (208) connected to an output coil (207) of the air core transformer (205), the comparator circuit (208) configured to provide an output signal (504) responsive to detection of voltage pulses across the output coil (207).