tailieunhanh - Báo cáo hóa học: " Research Article An Adaptive Constraint Method for Paraunitary Filter Banks with Applications to Spatiotemporal Subspace Tracking"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article An Adaptive Constraint Method for Paraunitary Filter Banks with Applications to Spatiotemporal Subspace Tracking | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2007 Article ID 80301 11 pages doi 2007 80301 Research Article An Adaptive Constraint Method for Paraunitary Filter Banks with Applications to Spatiotemporal Subspace Tracking Scott C. Douglas Department of Electrical Engineering School of Engineering Southern Methodist University . Box 750338 Dallas TX 75275 USA Received 1 October 2005 Revised 8 April 2006 Accepted 30 April 2006 Recommended by Vincent Poor This paper presents an adaptive method for maintaining paraunitary constraints on direct-form multichannel finite impulse response FIR filters. The technique is a spatiotemporal extension of a simple iterative procedure for imposing orthogonality constraints on nearly unitary matrices. A convergence analysis indicates that it has a large capture region and its convergence rate is shown to be locally quadratic. Simulations of the method verify its capabilities in maintaining paraunitary constraints for gradient-based spatiotemporal principal and minor subspace tracking. Finally as the technique is easily extended to multidimensional convolution forms we illustrate such an extension for two-dimensional adaptive paraunitary filters using a simple image sequence encoding example. Copyright 2007 Hindawi Publishing Corporation. All rights reserved. 1. INTRODUCTION Paraunitary filters and their one-dimensional cousins allpass filters are important for a number of useful signal processing tasks including coding deconvolution and equalization beamforming and subspace processing 1-12 . Paraunitary filters are lossless devices such that no spectral energy is lost or gained in any targeted spatial dimension of the multichannel input signal being filtered. The main use of paraunitary filters is to alter the phase relationships of the signals being sent through them. They are also typically used to reduce the spatial dimensionality of a multichannel signal with a minimal loss of