2D space–time wave-digital multi-fan filter banks for signals consisting of multiple plane waves

• Published in: Multidimensional systems and signal processing 2014, Vol.25 (1), p.17-39
• Main Authors: Rajapaksha, Nilanka, Madanayake, Arjuna, Bruton, Leonard T.
• Format: Article
• Language: English
• Subjects: Artificial Intelligence; Circuits and Systems; Electrical Engineering; Engineering; Signal,Image and Speech Processing
• ISSN: 0923-6082; 1573-0824
• DOI: 10.1007/s11045-012-0183-6

Two dimensional space–time fan filters may be used for the highly-selective enhancement of spatio-temporal plane-waves on the basis of their directions of arrival. Unlike uniform bandwidth beam filters, ideal fan filters transmit passband signals over a range of directions of arrival that is independent of their 1D temporal spectrum. In this work, closed-form 2D wave-digital filter design equations and corresponding hardware architectures are proposed for realizing M independent fan-shaped passbands having independently steerable directionality and selectivity. A design method based on LCR ladder networks is proposed and implemented using a 2D time-multiplexed raster-scanned architecture that is suitable for low frequency applications such as audio, multimedia, seismic and ultrasonic beamforming. The architectures are designed, simulated, physically realized and tested on FPGA-based prototypes. Examples of 2D IIR M-fan filterbanks with FPGA implementations, together with measured results from on-chip hardware verifications, show the successful design and hardware realization. The filterbanks and hardware architectures are shown to be suitable for real-time sensor-array beamforming applications using custom VLSI circuits.