Off-broadside main beam design and subband implementation for a class of frequency invariant beamformers

Liu, W. and Weiss, S. (2009) Off-broadside main beam design and subband implementation for a class of frequency invariant beamformers. Signal Processing, 89 (5). pp. 913-920. ISSN 0165-1684

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Abstract

The design of frequency invariant beamformers (FIBs) with off-broadside main beams is studied and it is shown that the required FIR filter length in this case should be much larger than the one with a broadside main beam. To reduce the computational complexity of such a beamformer and also improve its frequency invariant property at lower frequencies, two subband implementations are proposed. in the first one, the fullband array signals are split into subbands by a bank of analysis filters and the corresponding decimated subband signals form a series of subband arrays, Based on this standard subband structure, we then change the sensor spacings of different subband signals so that lower frequency bands have a larger spacing. which leads to a class of FIBs with scaled aperture with further improved performance at lower frequencies.