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 multifrequency signals in 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 that appears when the rotation frequency changes slowly. This second method uses an additional sensor, giving one pulse per revolution, to transform the input (asynchronous) signal into a synchronous signal having a fixed number of samples per revolution. The performance and effectiveness of both procedures are illustrated by means of simulation examples.