作者：
Binde, SSiemens AG
Publ Commun Networks Grp Switching Networks Dev Periphery Syst D-81359 Munich Germany
In this paper a new stabilization method for the problem of numerical instability of fast recursive least-squares algorithms is introduced. The new approach arose from implementation aspects of common stabilized fast ...
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In this paper a new stabilization method for the problem of numerical instability of fast recursive least-squares algorithms is introduced. The new approach arose from implementation aspects of common stabilized fast transversal filters (SFTF) algorithms in the compensation of acoustical echoes. Real-time situations are characterized by nonpersistent excitation and time-variant systems. Analysing these cases we found out insufficiencies in the performance of SFTF algorithms that exploit redundancy by feedback of numerical errors. Out of these results arose a new concept to cope with stabilization problems: A leakage in the prediction part of the FTF algorithm turned out to make the algorithm very stable and robust, The new found Leaky FTF (LFTF) algorithm, first derived in (Binde, 1995), is analysed in this article. It has proven to be stable given an appropriate value for the leakage factor. (C) 1998 Elsevier Science B.V. All rights reserved.
A fast version of the multichannel QR algorithm for rls adaptive filtering, with channel filters of unequal length, is derived. This is achieved by applying the techniques of algorithmic engineering to a signal flow g...
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A fast version of the multichannel QR algorithm for rls adaptive filtering, with channel filters of unequal length, is derived. This is achieved by applying the techniques of algorithmic engineering to a signal flow graph representation of the basic QR rls algorithm. By virtue of this graphical approach, the derivation is relatively straightforward and circumvents the complex and notationally verbose matrix algebra usually involved in the derivation of fast rls algorithms in general and the previously published, unequal-length, multichannel rls lattice algorithm in particular.
This paper presents a new structure for noise and echo cancelers based on a combined fast adaptive algorithm. The main purpose of the new structure is to detect both the double-talk and the unknown path change. This g...
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This paper presents a new structure for noise and echo cancelers based on a combined fast adaptive algorithm. The main purpose of the new structure is to detect both the double-talk and the unknown path change. This goal is accomplished by using two adaptive filters. A main adaptive filter F-n, adjusted only in the non-double-talk period by the normalized LMS algorithm, is used for providing the canceler output. An auxiliary adaptive filter F-f, adjusted by the fastrls algorithm, is used for detecting the double-talk and obtaining a near optimum tap-weight vector for F-n in the initialization period and whenever the unknown path has a sudden or fast change. The proposed structure is examined through computer simulation on a noise cancellation problem. Good cancellation performance and stable operation are obtained when signal is a speech corrupted by a white noise, a colored noise and another speech signal. Simulation results also show that the proposed structure is capable of distinguishing the near-end signal from the noise path change and quickly tracking this change.
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