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A method is presented for active cancellation of crosstalk effects in ultrasonic arrays. The approach makes use of the programmable transmitter waveform generators that are now being used with growing prevalence in diagnostic ultrasound systems. The array's transmit mode transfer function is represented by a transfer function matrix. Elements of this matrix are determined by exciting a single, central element with a wideband waveform and determining the resulting pressure output from the central element and adjacent elements. The desired output then is defined (e.g., finite output from a single, central element) and zero output from all other elements. The transfer function matrix equation can be solved to determine the required excitation functions on both the central array element and its neighbors. These excitation functions result in reduced evidence of crosstalk on the output signals. Therefore, the single-element, angular-response function is improved. Using superposition, the approach can be extended to beamformed array excitation. A variety of theoretical and experimental results are shown. The method also can be used in the receive mode but with a less satisfactory solution. A transmitting mode experiment based on a prototype five-element transducer has provided results indicating that sidelobes in the angular response can be reduced using this technique.
Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on (Volume:50 , Issue: 12 )
Date of Publication: Dec. 2003