Aliasing frequencies detection circuit - compares frequency spectra of two irrationally sampled signals to detect aliasing frequencies prior to A=D conversion

摘要

A sensor-derived time-dependent analogue input signal (E) is passed to two identical equidistant digital sampling units (1,2) that have irrational sampling frequencies, f1 and f2. These units produce time-dependant sampled digital outputs (F1,F2) which are passed to an identical pair of discrete Fourier Transform units (3,4) that extract the real-time constituent frequency components (S1,S2) from the sampled digital signals. The constituent frequency components signals are then passed to a spectral comparator unit (5) that compares either the instantaneous or the rank correlation spectra of all or part of the frequency component signal range and generates a correlation value (A) that indicates whether there is a possibility that aliaising signals are present. USE - Aliasing indication enables sampling frequency to be increased to subsume any aliasing errors within acceptable tolerance boundaries.