POWER LINE CARRIER TRANSMITTING AND RECEIVING DEVICE

摘要

PURPOSE:To obtain a correct waveform for an output of a demodulation circuit including an error signal by eliminating the effect of a band pass filter circuit on the characteristic due to the impedance change of a load connected to a power line by an amplifier circuit and using a waveform shaping section and a delay circuit to waveform-shape the disturbance in the waveform and using majority logic. CONSTITUTION:A carrier signal superimposed on a power line 1 is extracted by a high-pass filter 3 used in common for a coupling circuit with the power line 1 and the impedance is made stable by using an amplifier circuit 8 compensating the characteristic change in the high pass filter circuit 3 due to the impedance change in the load connected to the power line 1. Then a desired carrier signal is selected by a band pass filter circuit 4, the signal is demodulated by a demodulation circuit 5 and waveform-shaped by a waveform shaping section 9 and fed to other device 11 connected to receive a digital signal via an interface section 10. The delay circuit 12 shapes the disturbance of the output waveform of the demodulation circuit 5 and gives it to the shift register 14. A majority decision circuit 15 outputs a high level when lots of high levels exist in the contents of the shift register 14.