Laser Doppler vibration measuring system using bispectral analysis

Abstract

A new laser Doppler vibration measuring method, which operates correctly even in fairly large disturbing Gaussian noise, is developed. In this method the amplitude and phase of vibration are extracted by bispectral analysis between the detected and reference signals so that the significant bispectral characteristics of the detected signal, which reflects the frequency modulation by the vibration, is used. Application of the bispectral analysis excludes disturbing Gaussian noise, resulting in realization of a measuring system effective even under noisy circumstances. The experimental results show clearly the usefulness of the proposed method.