DIRECTIONAL WIGNER DISTRIBUTION FOR ORDER ANALYSIS IN ROTATING/RECIPROCATING MACHINES

A signal processing technique for rotation-related transient signals from a rotating or reciprocating machine is proposed to characterise its instantaneous planar motion. It essentially utilises the directional Wigner distributions (dWDs) defined for the forward and backward pass analytic signals. It is shown that the auto- and cross-dWDs in the angle-order domain are much better in concentration of signal terms and reduction of interference terms than those conventionally defined in the time-frequency domain, particularly when the rotational speed variation is significant during acquisition of the signals.