A communication system includes a transmitter and a receiver connected through a cable. The transmitter transmits a first signal to the receiver using a voltage applied to the cable. A control circuit of the receiver receives the first signal and transmitting a second signal to the transmitter using a current flowing to the cable. A charging circuit of the receiver performs a charging operation by receiving the voltage through the cable and supplying a driving voltage to the control circuit. The control circuit includes a filter generating a second voltage by extracting a voltage within a reference range from a peak voltage of a first voltage and a voltage meter extracting the first signal by measuring the second voltage.