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

  • Authors:
  • Wei Liu;Stephan Weiss

  • Affiliations:
  • Communications Research Group, Department of Electronic and Electrical Engineering, University of Sheffield, UK;Centre for excellence in Signal & Image Processing, Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow, UK

  • Venue:
  • Signal Processing
  • Year:
  • 2009

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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.