Loudspeaker analysis: A radar based approach

Abstract

Recently, radar based micro-Doppler signature analysis has been successfully applied in various sectors including defence, biomedical, and automotive. This article presents the novel use of radar micro-Doppler for loudspeaker analysis. The approach offers the potential benefits of characterizing the mechanical motion of a loudspeaker in order to identify defects and design issues. Compared with acoustic based approaches, the use of radar allows reliable measurements in an acoustically noisy end of a production line. In addition, when compared with a laser vibrometric approach, the use of radar micro-Doppler reduces the number of measurements required and provides direct access to the information of the metallic components of the loudspeaker. In the paper experimental results and analysis of the micro-Doppler signatures of loudspeakers using low cost radar systems are presented. Based on Thiele&Small parameters, the voice coil displacement is modelled and micro-Doppler signatures for a single tone and a sine sweep stimulus are presented. Furthermore, in order to characterize the speaker with a single radar measurement, a methodology to measure mechanical frequency response of loudspeakers is also shown.