Application for Selecting Filtering Parameters to Obtain Envelope Spectra

Envelope analysis of a signal in digital signal processing (DSP) is a very well - known approach in the detection and identification of faults within condition monitoring systems for many years. In general, enveloping techniques are used to extract the second order cyclo - stationary components like the periodic structural responses generated by the faulty rolling element bearings (REB). The modulations of GMF (Gear Mesh Frequency) and the amplitude modulations (AM) of the bearing characteristic frequencies can be visualized by the envelope signal. Typically, envelope analysis is used as a benchmark method for REB diagnostics along with the visualization of its additional amplitude modulation (AM) and for the visualization of amplitude modulated gearbox - generated deterministic and random components. In digital signal processing, filters and their methodologies play a vital role in analyzing a signal. In recent times, the MATLAB programming tool has been a very advanced tool as it provides various insights into scientific research. In this paper, a novel methodology is used in the design and development of a user - interactive application using the MATLAB “appdesigner” tool for selection of the filtering parameters to obtain the respective envelope signal and envelope spectrum for a real vibration signal acquired from the rotary machine. The methodology for designing this application includes four unique paths for selecting the respective filtering techniques which are based on the high - pass and low - pass 4th order Butterworth IIR filters (Infinite Impulse Response filters) along with Hilbert transform. The signal generated from the rotary machine is utilized and processed in this application to obtain the necessary envelopes (i.e., envelope signals and envelope spectr ums) of the original time waveform. The paper compares time / angle domain calculations with Hilbert transform - based calculations.