Electrical filter and signal discriminating apparatus employing the same

摘要

The disclosure relates to an improved signal discriminating apparatus which includes an electrical filter having as a central frequency, a value between the frequencies of two signals different from each other in frequency the presence or absence of each of which in a carrier signal is to be detected, circuitry for discriminating whether at least one of the two signals different from each other in frequency and is present in the carrier signal, and further circuitry for discriminating the phase difference between the input and the output sides of the filter.