| 摘要 |
PURPOSE:To compare a threshold signal and a detected signal, to detect the presence and absence of the combination of a composite frequency by the compared result and to receive only a regular signal, by selectively detecting plural frequency components with a filter bank and outputting the threshold signal to be proportional to the total power of an input signal from a threshold signal generator. CONSTITUTION:A multiplexing signal is detected to combine plural m(n>m) frequencies out of plural (n) numbers of frequencies which are prepared in advance, and to be outputted by a multi-frequency detecting device. By BPFs11-1n, which are prepared in advance, of a filter bank 1 of this system, the respective frequency components are selectively outputted. By a threshold signal generating part 2, the threshold signal for signal detection to be proportional to the total power of the input signal is outputted. The threshold signal of this generating part 2 and the output signal detected by the bank 1 are compared by a comparator part 3 and according to the compared result of the comparator part 3, the presence and absence of the combination of the plural numbers (m) is detected by a detecting part 4. Then, only the regular signal is received. |
