Wideband delay-sum digital aperture using Thiran all-pass fractional delay filters
Conference
Madanayake, A, Udayanga, N, Ariyarathna, V. (2016). Wideband delay-sum digital aperture using Thiran all-pass fractional delay filters
. 10.1109/RADAR.2016.7485288
Madanayake, A, Udayanga, N, Ariyarathna, V. (2016). Wideband delay-sum digital aperture using Thiran all-pass fractional delay filters
. 10.1109/RADAR.2016.7485288
A delay-And-sum wideband beamforming architecture is proposed employing digital fractional delays realized via Thiran recursive all-pass filters. FIR filter based fractional delay approximation blocks that are used in standard delay-And-sum beamformers are replaced by Thiran all-pass fractional delay filters. Thiran filters-which are of IIR type-provide maximally flat group delay compared to other IIR fractional delay approximations. The digital hardware complexity for wideband beamformers is dominated by parallel multipliers in the signal processing system. Proposed wideband beamformer provides better performance in terms of the bandwidth and the flatness of the magnitude response, compared to FIR-filter based beamformers for a given level of digital hardware circuit complexity. It shows a 20% increase in the operational bandwidth compared to the method that calculates filter coefficients using the Lagrange interpolation. The proposed Thiran-filter based beamformer is realized on the ROACH-2 FPGA hardware platform for 16-and 8-element antenna arrays. A Xilinx Virtex-6 based FPGA prototype operates at a clock frequency of 357 MHz for full-band beamforming.
