The Min-Norm Beamformer: A new estimate of the propagation speed of waves in a car exhaust

In this paper we present a new estimate of the propagation speed of acoustic waves propagating along a pipe based on array signal processing, the so-called Min-Norm Beamformer (MNB). In a previous contribution [1], the authors had already presented the formulation of this new estimate for narrowband signals, but the scenery of acoustic waves uses to be broadband. Therefore, we establish now the complete formulation of the MNB estimate for broadband waves for the two unique possible situations: a coherent or an incoherent processing of the data Sample Covariance Matrix (CSM), including the most efficient matrix transformations given in the literature [2] [3]. Finally, we present several results for three experiments carried out in a real environment : a car exhaust with three different engines at work.