METHOD FOR SPECTRAL ANALYSIS OF SIGNALS Russian patent published in 1997 - IPC

FIELD: instruments for detection of ratio of harmonic constituents in signal, in particular, infra-low frequencies. SUBSTANCE: method involves conversion of input periodic signal and measuring result on indicator which provides time intervals for analysis, generation of reference sine-shaped signal which frequency is equal to first harmonics of input signal, detection of time intervals inside each half-wave of reference sine signal. Said time intervals are limited by time moments are spaced from middle of corresponding half wave of reference sine signal by quarter of half-period. The method involves measuring of two instantaneous input values for start and end of selected interval, calculation of square root of sum of squares of corresponding pair of instantaneous values, multiple phase shift of one signal with respect to another. For each shift square roots of corresponding pairs of instantaneous input values are detected. Absolute values of difference between calculations is used for judging about higher harmonics in input signal. EFFECT: elimination of narrow-band filters, increased speed, increased precision, simplified design. 2 dwg