Radar micro-Doppler for loudspeaker analysis: an industrial process application

Abstract

In the last decades a strong interest has developed on radar micro-Doppler analysis targeting applications in a number of sectors including defence, bio-medical and automotive. This paper investigates for the first time the use of radar micro-Doppler for loudspeaker analysis. This approach offers the potential benefits to characterize the mechanical motion of a loudspeaker and to identify defects and design issues. Compared with acoustic based approaches, the use of radar information allows reliable measurements in an acoustically impaired environment. In addition, when compared with a laser vibrometric approach, the use of 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 are presented.

Radar Based Loudspeaker Measurements

“…A more complete analysis is achieved when chirp signal x (t) in ( 3) is used. According to loudspeaker theory, the displacement ῆc is a time varying function of fv(t), as described in (1). For an exponential sine sweep, the instantaneous vibration frequency fv(t) is defined as:…”

“…In this paper we want to discuss possible applications of the technology presented in [1], [2], [3]. In particular the use of radar micro-Doppler paired with sine-sweep measurements will be shown to be a powerful method to retrieve the mechanical response of an electro-dynamic loudspeaker, as well as a versatile End Of Line (EOL) classifier algorithm.…”

Loudspeaker Analysis: A Radar Based Approach

“…with λ the wavelength of the transmitted signal. Substitut-284 ing (7) in (4) the received signal can be expressed as [12]:…”

“…The interest in micro-Doppler suggests that this technology is reliable, and that it is worth investigating it in further applications domains, such as the acoustic one. In [12], the authors introduce for the first time a novel approach based on radar micro-Doppler to analyse and measure the return from loudspeaker. This approach is motivated by the potential cost effectiveness and operational advantages that a radar based approach could introduce over acoustic and laser based ones.…”