The use of correlation systems for real-time ultrasonic imaging

In previous studies, we have shown that correlation systems can overcome the peak-power limitations of conventional pulse-echo systems in non-moving target applications. This study examines the applicability of correlation systems to practical real-time imaging situations involving moving targets and clutter. The study was carried out through simulations of the generalized ambiguity function and a derived system signal-to-noise ratio formula. Results indicate that whether a correlation system is better than a conventional system depends on the target velocity and the clutter-to-noise ratio, and that special pseudo-random Golay codes provide the best overall- .correlation system performance. Although the special Golay code properties of self-noise and crosscorrelation cancellation are diminished as the velocity of a target increases, the degradation of system performance was found to be minimal for all but the fastest moving targets in medical imaging applications.