During ultrasonic testing, it is possible to analyze the images of reflectors restored by the digital focusing antenna (CFA) method. To improve the image quality of reflectors, instead of summing echo samples by calculated delays, you can use the coherence coefficient (CF) or the sign coherence coefficient (SCF). Images obtained with the calculation of the coherence coefficient make it possible to increase the signal-to-noise ratio and frontal resolution. Numerical and model experiments have shown the effectiveness of restoring CF or SCF images of reflectors, both when registering echo signals with conventional antenna arrays and with thinned (PRAR) ones, in which the distance between the elements is greater than the wavelength.
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