Beamforming for broadband constant beamwidth based on FIR and DSP

A method to design a beamformer for broadband constant beamwidth. is presented. Constant beamwidth is important in sonar systems for sea bottom observation and classification applications. For a given frequency band, a number of frequency points are chosen to represent the response of an arrary element. For each. frequency point a beamforming weight vector can be deduced to satisfy the given beamwidth requirement by existing methods. Therefore, for a broadband array of N elements, each row of the N • M weighting matrix represents the frequency response of an element of the array which can be satisfied by a FIR filter designed by model - reference adaptive technique. The sum of outputs from a bank of N FIR filters provides a beamformed output and so it is very handy to be implemented by DSP hardware.