Circuit arrangement for determining the cycle duration of the fundamental oscillation of band-limited and/or errored quasi-periodic signals in real time

摘要

The invention achieves the object of determining the cycle duration T0 of the fundamental oscillation from a band-limited and/or errored quasi-periodic signal through hardware implementation in real time. It is an essential feature, particularly in the case of speech and speaker recognition. The basic mode of operation is shown in the Figure. The signal s11 is amplitude-normalised (11) and then manually limited in such a way (12) that noise components no longer occur. The amplitude-normalised signal s14 is squared (14) so that the frequency of the fundamental oscillation and the frequencies of its harmonics are reconstituted. By means of a low-pass filter (15, 16) which is standardised in terms of signal processing to the fundamental frequency f0, the frequency range is limited to the frequency corresponding to three times the fundamental frequency, but not exceeding 500 Hz. With a controllable low-pass filter (16), the signal s17 is then band-limited (20, 17) in such a way that essentially only the fundamental oscillation is fed to the coder (18). From the positive and negative maximum values of the signal s18, the coder (18) generates a binary signal s19 whose cycle duration T0 is measured in the evaluation stage (19). IMAGE