| 摘要 |
PURPOSE:To detect the similarity of analog signals in a short time by inputting them to an analog multiplier, and detecting a magnitude of a signal obtained by passing its output through a low-pass filter. CONSTITUTION:Two signals are input to an analog multiplier 1, and analogously multiplied by one another. If the two signals contain the same frequency components, a product of the components is output as a DC, while if the two signals contain different frequency components, AC outputs of a sum and a difference of the frequencies are obtained. When the output signal is passed through a low-pass filter 2, its AC component is removed, and a DC component is output. This output is varied according to similar degree of the two analog signals, if the degree is high, its output is high, while if the degree is low, its output is low. A deciding circuit 3 detects the similarity of the two signals according to the magnitude of the output. |
