| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that the resolution of the A/D conversion of a distribution cycle signal with a level lower than that of a noise A/D-converted in bloc becomes narrow, and a signal detection becomes indistinct in reception when the noise with a high level exists other than the signal of a carrier transmitting device for a distribution line transmitted simultaneously by a plurality of distribution cycle because the conversion width of an A/D conversion circuit is determined by the noise voltage. SOLUTION: The device is provided with an FFT processing means 13 to perform the batch A/D conversion of inputted signals and to perform a fast Fourier transform for detecting an individual frequency in the inputted signals, a transmission circuit 30 provided before an A/D conversion circuit 11 and capable of opening and closing control, and a plurality of filters 31-34 provided in parallel with the transmission circuit 30, respectively, for attenuating a frequency area other than a distribution frequency and capable of opening and closing control. When the frequency F of the maximum receiving level selected by performing FFT treatment to the transmission circuit 30 in a state of conduction is other than the distribution frequency, the transmission circuit 30 is made into non-conduction and a filter dealing with the maximum receiving level frequency is operated, then demodulation data processing is performed when the frequency of the maximum receiving level coincides with the distribution frequency.
|
