A novel hardware configuration for an adaptive beamforming array using quadrature mirror filter banks

The performance of a novel multirate subband adaptive beamforming array is evaluated. Instead of the traditional fast Fourier transform (FFT) filter t he quadrature mirror filter (QMF) bank is used here to partition or to subb and the incoming signal frequency band. The QMF bank divides the spectrum i nto the lower and higher subbands. Beamforming is then carried out pw both of these subbands. In this paper, the same concept is used, except for the fact that only one of the two subbands (in our case. the lower) is optimize d for the desired subband output This signal is then passed through a multi plier or a transformer, which generates the same output ns the other subban d (in our case, higher). Both the optimized and transformer outputs are the n combined to produce the final signal. This method reduces the circuit com plexity ns well as the cost of the subband adaptive beamformer. The radiati on responses, the mean-square errors, and the eigenspectrums are subjected to investigation. It is observed that the beamforming performance ann the m ean-square errors (MSE) remain the same for both the previous and novel con figurations. (C) 1995 John Wiley & Sons, Inc.