FUNDAMENTAL WAVE DETECTOR

PURPOSE: To detect a basic wave with a high precision whatever state an inputted voice signal waveform is in by providing a first peak detection means which detects a positive peak of an inputted signal to make a pulse of it, a phase inverting means, and a second peak detection means which detects the positive peak value of the output signal of the phase inverting means to make a pulse of it. CONSTITUTION: When a signal (a) is inputted to an input terminal 1, a pulse waveform (b) is outputted to the output of a first peak detection means 3. Meanwhile, the output of a phase inverting means 2 has an inverted waveform (c) of the signal (a), and a pulse waveform (d) is outputted by a second peak detection means 4. The pulse signal generated from the positive peak value of the voice signal and that from the negative peak value are compared with each other to determine which pulse signal is based on the fundamental wave, and the period of the pulse signal having a longer average period value is stored in a prescribed RAM as the period of the basic wave in accordance with the comparison result. Thus, the basic wave of the voice signal is accurately detected whichever polarity side the peak of the fundamental wave exists on.