OPTIMAL AND WAVELET-BASED SHOCK-WAVE DETECTION AND ESTIMATION

Detection and estimation of aeroacoustic shock waves generated by supe rsonic projectiles are considered. The shock wave is an N-shaped acous tic wave emanating in the form of an acoustic cone trailing the projec tile. An optimal detection/estimation scheme is considered based on a parametric signal plus white Gaussian noise model. To gain robustness and reduce complexity, we then focus on gradient estimators for shock wave edge detection, exploiting the very fast shock rise and fall time s. The approach is cast in terms of a wavelet transform where the leve l of smoothing corresponds to scale. A multiscale analysis is describe d, consisting of multiscale products, to enhance edge detection and es timation. This method is effective and robust with respect to unknown environmental interference that will generally not exhibit singulariti es as sharp as the N-wave edges. Experimental results are presented fo r discriminating N waves in the presence of vehicle noise. Results are also shown, as a function of miss distance, for gradient-based detect ion of simulated small projectile shocks inserted into recorded tank n oise. (C) 1998 Acoustical Society of America. [S0001-4966(98)03008-2].