| 摘要 |
PURPOSE:To realize a small-sized, lightweight constitution and to obtain stable operation, by performing frequency discrimination through only digital circuits such as shift registers and a logical circuit. CONSTITUTION:A shift register SR1 inputs an input signal through a waveform rectifier and a shift register SR2 inputs plural reference signals read out of a memory MM1 successively; they are put in shifting operation by clock pulses CLK1 and CLK2. Outputs of corresponding stages of those shift registers SR1 and SR2 are inputted to inverted exclusive OR gates G1-Gn, whose outputs are summed up by an adder AD; when the output of the adder increases above the set value of a setter ST, a comparator CP generates an output 1. On the other hand, the read address of memory MM2 is specified corresponding to read contents of the memory MM1 and one of AND gates G11-G1n is turned on corresponding to the reference signal Sr from the memory MM1, so discrimination outputs D01-D0n are obtained according to the frequency of the input signal Si. |
