Improved ultrasonic detection using the analytic signal magnitude

An alternative to rectification is proposed for detection of an ultrasonic signal for medical or non-destructive evaluation applications. With this technique the envelope of the ultrasonic waveform is obtained by calculation of the magnitude of the complex analytic signal. An implementation, particularly suited for digital data processing, is presented which utilizes a fast Fourier transform for computation of the quadrature component of the received signal using the Hilbert transform. An ordinary transducer, pulser, and receiver are used together with a digital data acquisition system. The results of this processing are compared with conventional rectification, both with and without smoothing. The superior resolvability of two closely spaced interfaces on the A-mode presentation is clearly evident. Similar improvement in B-mode quality will result when an image is required.