THE USE OF TWO-DIMENSIONALLY SPARSE ARRAYS TO VISUALIZE THE SOUND FIELD RADIATED BY A MOVING VEHICLE, WITH APPLICATION TO MOTOR VEHICLE PASSBY TESTING

摘要

The primary goal of the present work was to develop a measurement technique that would add a diagnosticcapability to standard motor vehicle passby tests. It has been shown here that the representation of thesource velocity as a ftite order polynomial enables accurate and efficient de-Dopplerization of signalsreceived from sources moving with arbitrary velocity and acceleration. The amplitude correction strategydescribed in the present work makes the present approach different from classical beamformer approachesand allows source strengths and locations to be estimated with reasonable accuracy on an actual vehicleover the usual range of “look” directions encountered in a passby test. However, when the look directionwas too oblique (e.g., when the vehicle position was beyond approximately 10 meters from the arraycenter), this approach fails to locate the source locations accurately. Currently, a two-step method is underinvestigation, in which accurate source locations are resolved first by classical beamforming techniques,and then the correct source strengths at the identified source locations are restored by accounting for thespherical spreading effects.