Improved procedures for estimating amplitudes and phases of harmonics with application to vibration analysis

In this paper we propose two procedures for accurate amplitude and phase estimation of vibration signals of rotating machinery. The first method reduces the amplitude attenuation and phase shift caused by the “nonflat” top of the main lobe of the window. The second procedure is able to reduce not only the leakage effects due to windowing, but also the distortion in the amplitude and phase estimates when there is a slow change in the frequencies. Using an additional sensor giving one pulse per revolution, this method transforms the input (asynchronous) signal into a synchronous signal having a fixed number of samples per revolution. The performance of both procedures is illustrated by means of simulation examples