Digital beamsteering with recursive multichannel filters

Digital realizations of time-delay beamformers may employ discrete-time interpolation to effect the required beamsteering. An alternative to oversampling the array element signals, arithmetic beamformers exhibit reductions in sampling rate, data transfer rates, and memory at the expense of additional arithmetic operations. An improved design strategy, which has the potential of decreasing computational requirements for given beam response specifications, is presented here for FIR and IIR implementations of arithmetic interpolation beamformers. It is shown that recursive filters designed according to this approach can offer a potential performance advantage over FIR alternatives.