Implementation of Beamforming for Large-Scale Circular Array Sonar Based on Parallel FIR Filter Structure in FPGA
In this paper, the directivity of the circular array is analyzed, real-time beamforming algorithm of circular array in frequency domain similar to parallel FIR filter structure is proposed by using the characteristic of the same directivity in different directions and the characteristic of steer vector symmetry. The coefficients of parallel FIR (Finite Impulse Response) filters are constant, while the steer vector of each frequency in the beamforming algorithm is variable, so the coefficients (steer vector) of the beamforming parallel filter need to be dynamically changed according to the frequency points. For frequency domain beamforming of high frequency large-scale circular array sonar, this algorithm only needs two shift registers, complex multipliers which is half the number of elements used in beamforming and a few logic resources to calculate steer vector in FPGA (Field Programmable Gate Array), and the algorithm can run at a higher working frequency. The lake-trial result shows that this parallel algorithm satisfies the real-time requirements of high-frequency large-scale circular array sonar, and the sonar has good azimuth resolution and detection performance.
KeywordsCircular array Directivity Beamforming Parallel structure FPGA
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