Mirroring Properties of Sub-band Adaptive Beamforming Arrays using Quadrature Mirror Filter Banks
The concept of the sub-band adaptive beamforming arrays (ABA) is derived from the conventional fullband adaptive antenna arrays. Instead of doing the beamforming for the entire frequency band as in the full band ABA, only one sub-band of the frequency band is subjected to the same in here. The sub-banding of the full frequency band is done here by a quadrature mirror filter (QMF) bank. In a previous attempt, an approximate method has been proposed to reproduce the higher sub-band output from the lower sub-band output . However, the higher sub-band has higher centre frequency, which demands higher Nyquist bandwidth. This will increase the operational complexity of the sub-band ABA. Recently it has been shown that the QMF sub-band adaptive beamforming can be performed by optimising the higher sub-band output and then, multiplying the signal output with a transforming factor that generates the lower sub-band output . The lower frequency band requires only lower Nyquist bandwidth. It is believed that this will reduce the hardware complexity, the cost and the workload of the earlier version of the QMF sub-band ABA system . In this work, a hardware implementation and its characteristics of such a sub-band ABA to generate the combined output from the higher sub-band is investigated.
KeywordsMicrowave Covariance Radar Malaysia Sonar
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- 2.S. Chandran, “A novel scheme for a sub-band adaptive beamforming array implementation using quadrature mirror filter banks”, IEE Electronics Letters, 39,12, pp. 891–892, June 2003Google Scholar
- 4.S. Chandran and M. K. Ibrahim, “Adaptive beamforming techniques using QMF”, IEE Proc. Int. Conf. On Antennas and Propagation, Vol.1, pp. 257–260, Eindhoven, April 1995Google Scholar
- 6.P. P. Vaidyanathan, Multirate Systems and Filter Banks, 1992, NJ: Prentice-Hall, Englewood CliffsGoogle Scholar
- 7.V. K. Jain, V. K. and R. E. Crochiere,“Quadrature mirror filter design in the time domain”, IEEE Trans ASSP., 32, pp. 353–361, 1984Google Scholar
- 8.S. Haykin, Adaptive Filter Theory. 1991, NJ: Prentice-Hall, Englewood CliffsGoogle Scholar
- 11.J. D. Johnston, “A filter family designed for use in quadrature mirror filter banks’, in Proc. 1990 ICASSP, pp. 291–294, April 1990Google Scholar