Imaging sensor system using rectified delay-and-multiply operations with an ultrasonic array

This paper describes an imaging sensor system that uses rectified delay-and-multiply operations with an ultrasonic array. Delay-and-sum operations are generally used for synthetic aperture systems; however, greatly improved directivity spectra can be obtained using the new system. The side lobe in the sensor directivity is very small, and it is easy to determine the threshold level of the signal. The characteristics of the system are evaluated by numerical simulation. In addition, its advantages are demonstrated by experiment. Since this system minimizes the possibility of privacy violation, it is suitable for measuring the shapes of three-dimensional objects in residential areas.