| 摘要 |
PROBLEM TO BE SOLVED: To provide a small radio communication instrument for a meter, which counts time with high accuracy, does not require a power supply circuit such as a transducer inside the instrument nor require securement of insulation distance in a circuit board.SOLUTION: A sensor 8 of a radio communication instrument 1 is certainly and electromagnetically coupled to a power supply line 5a for supplying commercial power supply to a watt-hour meter 2. A waveform shaping circuit 9a performs waveform shaping of a magnetic field detection signal to be output from the sensor 8 by a high-impedance amplifier circuit and outputs it to a low-pass filter 9b. The low-pass filter 9b extracts commercial frequency components from the signal for which the waveform shaping is performed by the waveform shaping circuit 9a and outputs them to a clock pulse making circuit 9c. The clock pulse making circuit 9c generates time count pulses from the commercial frequency components extracted by the low-pass filter 9b. The watt-hour meter 2 performs an operation based on time by using the time count pulses generated by the time count pulse generation means 9. |
