Adaptive noise cancellation in the intercept time-slowness domain for eliminating ultrasonic crosstalk in a transducer array

Abstract

Ultrasonic waves, acquired by an array probe, are likely interfered by the crosstalk signals due to intercommunication among the elements. The crosstalk signals are not desirable and mixed with the main signals, degrading the data quality. In this work, we choose a filtering strategy to separate crosstalk and the desired signals. We design a traditional adaptive crosstalk canceller (ACC) in the Radon (intercept time, τ and slowness, p) domain. A Normalized-Least-Mean-Square strategy is used to determine the filter coefficients. Formulating the filter in the τ-p space has the merits to efficiently remove random noise and significantly enhance signal-to-noise ratio. The filtered Radon panels are then transformed back to the t-x space using the inverse Radon transform. The robustness and accuracy of the filter are studied using simulated noiseless and noisy data sets. The filtered signals tracks well with the simulated noiseless signals with an average mean-square-error (MSE) of 11%. Finally the ACC is applied to an experimental data set of a 2.4-cm thick Plexiglas plate. The result has demonstrated the ACC effectively recovered the main arrivals with reasonable coherency and continuity.