METHOD AND APPARATUS FOR DETERMINING RESONANCE INFORMATION

摘要

The present invention is a method and system for accurately analyzing shaft encoder signals from rotating machines. The invention reduces noise and other interferences in the encoder signals by novel means that yield an unprecedented power for extracting useful information. Signal distortion due to variation in the rotation rate of the machinery and due to FFT leakage are eliminated by acquiring digital values of the encoder signals at a set of discrete times that are determined by the properly averaged rotation rate of the shaft and requiring a fixed integer number of these discrete times per rotation of the shaft. Amplitude modulation is eliminated by proper spectral combination of left and right sidebands of the main encoder signal. Additive noise is removed by multiplying sidebands and averaging the results over a number of data records.