Algorithms for spectrum background estimation of non-stationary signals. (15th March 2022)

• Record Type: Journal Article
• Authors: Matania, Omri; Klein, Renata; Bortman, Jacob
• Is Part Of: Mechanical systems and signal processing. Volume 167:Part A(2022)
• Publication Date: 2022-03-15
• Subjects: ACS adaptive clutter separation -- Ceps-Lift liftering in the cepstrum domain -- CBM condition-based maintenance -- COBE cycle-order background estimation -- DFT discrete Fourier transform -- IDFT inverse discrete Fourier transform -- IS instantaneous speed -- MOPA multi-order probabilistic approach -- OLP overlapping percentage -- OMA operation modal analysis -- PSD power spectral density -- RPS revolutions per second -- SA synchronous average -- SNR signal-to-noise ratio -- TFBE time–frequency background estimation; Pre-whitening -- adaptive clutter separation (ACS) -- Cepstrum liftering -- Background -- Non-stationary signal -- Dephase; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2021.108551
• Languages: English
• ISSNs: 0888-3270

Abstract

Highlights: Review of current techniques for background estimation of non-stationary signals. Background estimation of non-stationary signals by TFR for unknown IS. Improved Background estimation of non-stationary signals by cycle-order processing. Abstract: The spectrum background, or in short, the background, is associated with the slow variations of the spectrum. The estimated background can be used to pre-whiten the spectrum and to identify significant variations in machine structure. However, the known background estimation techniques have been considered mainly in the context of stationary signals. Thus, the goal of this paper is to present new algorithms for background estimation of non-stationary signals. Based on the examination of available techniques for separating discrete frequencies and the background, we present two new algorithms for non-stationary signals: (i) time–frequency background estimation (TFBE), recommended when the rotation speed is unknown, and (ii) cycle-order background estimation (COBE), recommended when the rotation speed is known. The performance of these two new algorithms is demonstrated using a large data bank composed of simulated vibration signals of rotating components in different rotating speed profiles combined with realistic transfer functions measured on different rotating machines. These vibration signals were designed for a comprehensive investigation of the capabilities and limitations of the new algorithms. The accuracy of the new algorithms to estimate the background depends on the rotating speed variation. Good estimations of the backgrounds were achieved for rotating speed variations up to 10 Hz/s. Furthermore, the abilities of the algorithms are illustrated on real measured data.