Patent ID: 8718571

Claim:
A transmitting and receiving device, comprising: a transmission circuit that transmits transmission data by FM-modulating a carrier wave of the transmission data, the transmission circuit including: a modulation pattern generator that generates modulation pattern data, a current-controlled oscillator that changes a cycle of a frequency modulation signal according to the modulation pattern data, and a modulation circuit that generates a communication signal by modifying an amplitude of the frequency modulation signal according to the transmission data; an FM demodulation circuit that generates a demodulation signal by FM-demodulating a received signal; a first filter circuit that changes a pass-band for letting the received signal pass through according to the demodulation signal; and a parallel resonance circuit that adjusts a resonance frequency to a first carrier frequency of the communication signal according to the modulation pattern data, and adjusts the resonance frequency to a second carrier frequency of the received signal according to the frequency demodulation data, wherein the transmitting and receiving device performs a power supply line communication through the power supply line in which a signal is transmitted and received among the plurality of transmitting and receiving devices.