| 摘要 |
PURPOSE:To find the frequency of fundamental wave from the signal that contains many higher harmonics by detecting the peak of periodic input signal wave form to obtain a pulse signal corresponding to the fundamental period of input signal, by discriminating the frequency band of signal and by sample-holding it. CONSTITUTION:The signal to be detected, which contains many higher harmonics, is fed to the peak value detecting circuit 1 to detect the peak value. Its output is provided to the octave separating circuit 3 as a hand discriminator through the shaping circuit 2. The output of octave separating circuit is fed to the frequency detecting circuits 4a-4n to detect the frequency of fundamental wave of input signal. Each of the frequency detecting circuits 4a-4n consists of a sampling hold circuit 32 that sample-holds the output of octave separating circuit, filter circuit 33, rectifier circuit 34 and light emission diodes 39-42. The light emission diode corresponding to the frequency band to which the fundamental frequency belongs is lighted. |
