High-resolution beam forming for ultrasonic arrays

Array processing techniques are common in radar, sonar, and medical ultrasound. However, little work has been reported on the use of array processing with airborne ultrasound. This paper describes the application of array beam forming to airborne ultrasound. It also introduces a processing method which allows the separation between receiving elements to he increased above the traditional λ/2 limitation. This has the effect of increasing the resolution significantly above that normally expected from traditional array processing methods. A full evaluation of the method is given, a full error analysis of the resulting system is provided, and a comprehensive set of results are presented. The angular and longitudinal resolution of the improved beam former are also derived