Sequential Synthetic Aperture Sonar System-A Prototype of a Synthetic Aperture Sonar System

A prototype of a synthetic aperture sonar system is presented which displays computationally reconstructed images on a CRT. The image information is obtained sequentially by the scanning in twodimensions of a transmitter-receiver unit which produces and detects pulsed ultrasonic waves. The system consists of the scanning transmitter-receiver unit, computing parts designed especially for image reconstruction, IC memory devices and a display unit including a CRT. The signal processing and the control of each part of the system are carried out computationally. The system repeats at each sampling point the processes of registration of the received signal, image reconstruction from the dataand display of the sequentially synthesized image. Typically, ultrasonic waves of 1 MHz are used in water, and the images for the case of scanning along a circle of 40 mm diameter are obtained in less than a minute. With the system described in this paper, various fundamental characteristics of synthetic aperture sonar are verified experimentally. In addition, a practical imaging effect similar to zooming in a TV camera is shown as an example of the versatility of the system.