| 摘要 |
<p>PROBLEM TO BE SOLVED: To attenuate only a signal which has a specific frequency component alone. SOLUTION: This digital filter consists of a zero-cross detecting circuit 4 which detects zero crossing of an input signal, a wavelength calculating circuit 5 which detects the wavelength from detected intervals of the zero crossing, a window comparator 6 which outputs a detection signal when the detected wavelength is within a range of set wavelength, and an interface 7 which decreases the gain of a gain control amplifier 2 when the detection signal from the window comparator is outputted continuously for longer than a specific time.</p> |
