Improvement of the imaging of moving acoustic sources by the knowledge of their motion

To obtain, as a function of frequency, the directivity and spatial distribution of an acoustic source in motion, we make it pass, at the velocity V, in front of a linear microphone array. In classical methods, as the numerical processings of the signals concern T - duration windows, there results that the spectral resolution is limited by the Doppler spreading effect on spectral lines, and also that the source imaging is deteriorated by the blurring effect (VT) whose order of magnitude may reach the dimensions of the source. The purpose of this paper is to propose a method which takes advantage of the knowledge of the source motion to suppress the Doppler and blurring effects through an appropriate choice of sampling times. We present the mathematical formulation, which is illustrated by real applications on vehicles (motor car and air cushion train).