| 摘要 |
PURPOSE:To find the frequency of fundamental wave easily with a simple configuration by detecting the peak if input signal wave form, by obtaining a periodic pulse signal on shaping said wave form, and by measuring the output of hold circuit which samples the reference signal by said signal. CONSTITUTION:The peak component of signal such as musical sound that contains higher harmonics is detected by the peak value detecting circuit 1, a periodic pulse signal that coincides with the period of detected signal is provided from the shaping circuit 2. This periodic pulse signal is fed to the detecting circuits 6a to 6n in parallel, which have the reference signal generators 12 the frequencies of which are distinct from each other, through the contact S1 of the switch 3. In the detecting circuit 6, the wave form of beat frequency of both the reference signal and periodic pulse signal is provided from the sampling hold circuit 11, the light emission diode 15 as a decision element emits light when the output, which passes the low-pass filter 13 and full-wave rectifier 14, exceeds a fixed value. |
