Maximum a posteriori deconvolution of ultrasonic signals using multiple transducers

A new method for deconvolution of ultrasonic pulse-echo measurements employ ing multiple-transducer setup is proposed in the paper. An optimal way of e stimating the material reflection sequence for a linear signal generation m odel using maximum a posteriori estimation is proposed. The method combines the measurements from a number of transducers covering different frequency bands yielding an optimal estimate of the reflection sequence. The main id ea of this approach is to complement the information unavailable from one t ransducer in some frequency bands with the information from the other trans ducers. The method is based on the assumption that the measurements are per formed using transducers with identical apertures and apodization, which ar e located exactly at the same position relative to the test object during t he measurement. An error analysis presented in the paper proves that when t he above assumptions are fulfilled, the proposed method, by utilizing more data for estimation, consistently yields more accurate reflection sequence estimates than the classical Wiener filter. Experimental evidence is presen ted using both simulated and real ultrasonic data as a verification of the correctness of the multiple-transducer model and the estimation scheme. An illustration of the advantages of the method is also given using real ultra sonic data. (C) 2000 Acoustical Society of America. [S0001-4966(00)02105-6] .