Imaging sensor system using a composite ultrasonic array

This paper describes an imaging sensor system that uses a composite ultrasonic array. Side lobes and grating lobes in sensor directivity appear in conventional ultrasonic arrays. However, these lobes are reduced in this new sensor system. The sensor system consists of four wide-area ultrasonic array units, which are each made up of eight small-area ultrasonic receivers. After applying delay-and-sum operations to each unit, delay-and-multiply operations are applied to the signals from the units. The characteristics of the system are evaluated and its advantages are experimentally demonstrated. As this system minimizes the possibility of privacy violations, it is suitable for measuring the shapes of three-dimensional objects in residential areas.