Design of Wideband Digital Array Beamformer Using the Variable Fractional Delay Allpass Filter

Abstract:

To solve the space dispersion (SD) problem which makes the beam formed deviate from its expected direction in wideband digital array beamforming, a new wideband digital array beamformer (WDBF) is designed by introducing an identical variable fractional delay (VFD) filter on each sensor. The VFD filter is an all-pass filter with an infinite impulse response, thus it requires less filter order compared with finite impulse response filter. Since the VFD designed is suitable within the whole fractional delay range of-0.5 to 0.5 in sampling interval, the new beamformer designed is suitable for any direction without redesigning the fractional delay filter. In this way, the real-time property of the new beamformer is guaranteed. Simulation results show that the VFD deigned in this paper is high in precision. Applying it in the new WDBF, the SD problem is solved and the beam formed approximates the ideal beam very well.

• Periodical: Applied Mechanics and Materials (Volumes 719-720)
• Pages: 826-832
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.719-720.826
• Online since: January 2015
• Authors: Kai Wu*, Tao Su, Jin Hao Pang
• Keywords: Iterative Method, Variable Fractional Delay Allpass Filter, Wideband Digital Beamformer

References

[1] W. Melvin and J. Scheer, Principles of Modern Radar: Advanced Techniques. The Institution of Engineering and Technology, (2013).

[2] M. Wang, S.J. Wu, S.Y. Yang, Time domain beamforming for UWB pulse signal, Chinese Journal of Radio Science , vol. 21, pp.239-243, April (2006).

[3] Z.C. Fan, H.Y. Li, Z.H. He, Wideband Digital Beamforming Based on Fractional Delay, Radar Science and Technology, vol. 6, pp.450-453, Dec. (2008).

[4] P.F. McManamon, et al., Optical phased array technology, Proceedings of the IEEE , vol. 84, pp.268-298, Feb. (1996).

[5] T.I. Laakso, V. Valimaki, M. Karjalainen, U.K. Laine, Splitting the unit delay [FIR/all pass filters design], IEEE. Signal Processing Magazine, vol. 13, pp.30-60, July (1996).

DOI: 10.1109/79.482137

[6] V. Valimaki, T.I. Laakso, Principles of fractional delay filters, 2000 IEEE International Conference on Acoustics, Speech, and Signal Processing, vol. 6, pp.3870-3873, (2000).

DOI: 10.1109/icassp.2000.860248

[7] C.C. Tseng, Design of 1-D and 2-D variable fractional delay allpass filters using weighted least-squares method, IEEE. Trans. on Circuits and Systems I: Fundamental Theory and Applications, vol. 49, pp.1413-1422, Oct. (2002).

DOI: 10.1109/tcsi.2002.803361