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IEEE Transactions on Circuits and Systems

Issue 7 • July 1987

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Displaying Results 1 - 21 of 21
  • Editorial

    Publication Year: 1987, Page(s): 705
    Cited by:  Papers (2)
    Request permission for commercial reuse | PDF file iconPDF (162 KB)
    Freely Available from IEEE
  • Conditions for designing strictly positive real transfer functions for adaptive output error identification

    Publication Year: 1987, Page(s):731 - 736
    Cited by:  Papers (62)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (598 KB)

    Strictly positive real (SPR) transfer functions are of importance in Adaptive systems theory. This paper addresses two issues related to finding a polynomialb(s)such thatb(s)/a(s)is SPR for alla(s)belonging to a set ofnth-degree Hurwitz polynomials{P}^ndefined by the magnitude bounds on the coefficients ofa(s). It is shown that irre... View full abstract»

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  • Convergence analysis of a frequency-domain adaptive filter with exponential power averaging and generalized window function

    Publication Year: 1987, Page(s):788 - 798
    Cited by:  Papers (37)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1216 KB)

    One of the advantages of a Frequency-Domain Adaptive Filter (FDAF) is that one can achieve convergence at a constant rate over the whole frequency range by choosing the adaptation constant for each frequency binlequal to the overall adaptation constant divided by an estimate of the input power at this frequency bin. A commonly used method, applied in this paper, to estimate the input po... View full abstract»

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  • Convergence of the RLS and LMS adaptive filters

    Publication Year: 1987, Page(s):799 - 803
    Cited by:  Papers (37)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (599 KB)

    The paper presents new convergence results for two adaptive filters: the RLS and LMS algorithms. Convergence of the exact RLS algorithm is studied when the forgetting factorlambdais constant, which enables the adaptive filter to track time variations of the optimal filter. It is shown that, in the steady state, the squared deviation of the adaptive filter from the optimal one admits, wi... View full abstract»

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  • Fundamental relations between the LMS algorithm and the DFT

    Publication Year: 1987, Page(s):814 - 820
    Cited by:  Papers (58)  |  Patents (76)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (687 KB)

    The digital Fourier transform (DFT) and the adaptive least mean square (LMS) algorithm have existed for some time. This paper establishes a connection between them. The result is the "LMS spectrum analyzer," a new means for the calculation of the DFT. The method uses a set ofNperiodic complex phasors whose frequencies are equally spaced from dc to the sampling frequency. The phasors are... View full abstract»

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  • Effect of element errors on half-power beamwidth of the Capon adaptive beamformer

    Publication Year: 1987, Page(s):743 - 752
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1144 KB)

    The Capon beamformer can perform accurate bearing estimation by taking advantage of the fact that for high input signal-to-noise ratios, the "adaptive beamwidth" is much narrower than the classical Rayleigh limit. This paper studies the effect of random antenna element errors on this adaptive beamwidth. The imperfections considered are amplitude and phase errors which are constant during the perio... View full abstract»

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  • A robust adaptive array processor

    Publication Year: 1987, Page(s):721 - 730
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1040 KB)

    A post-beam-former interference canceller (PIC) processes the signals derived from an antenna array by forming two beams using fixed beam-forming weights. The weighted output of the one beam, referred to as the interference beam, is subtracted from the other beam, referred to as the signal beam, which has a specified response in the signal direction. This paper presents an algorithm to adjust the ... View full abstract»

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  • The design of highly selective adaptive three-dimensional recursive cone filters

    Publication Year: 1987, Page(s):775 - 781
    Cited by:  Papers (27)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (792 KB)

    A simple method for the design of highly selective adaptive 3-D recursive cone filters is described. The cone-shaped passband is realized by cascading (multiplying) two 3-D transfer functions having wedge-shaped passbands of different orientations. Each 3-D wedge-shaped function is realized by employing a highly selective 2-D fan filter. The passband of each fan filter can be rotated to permit the... View full abstract»

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  • Efficient transversal and lattice algorithms for linear-phase multichannel filtering

    Publication Year: 1987, Page(s):804 - 813
    Cited by:  Papers (20)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1032 KB)

    A new family of fast algorithms for batch and adaptive computation of multichannel linear- and affine-phase filters is developed. Both lattice and transversal realizations in ordinary and suitable normalized forms are studied. An important feature of the proposed recursive theme (besides its notable computational advantages) is that it offers a remarkable symmetry and unification of expressions an... View full abstract»

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  • A new efficient adaptive cascade lattice structure

    Publication Year: 1987, Page(s):707 - 711
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (544 KB)

    A new cascaded lattice realization of nonlinear and linear phase finite impulse response filters based on an orthogonal polynomial approach is presented. An efficient least-mean-square-based adaptive algorithm is proposed to update the reflection coefficients, which minimizes the cost function with respect to the argument of a trigonometric function rather than the reflection coefficient itself. R... View full abstract»

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  • Experimentation with an adaptive noise-cancellation filter

    Publication Year: 1987, Page(s):753 - 758
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (992 KB)

    The presence of noise in speech has severely adverse effects on speech produced by a low-bit-rate voice terminal. This paper describes an adaptive noise-cancellation filter that was designed to suppress the broad-band, nonstationary, and intense noise often encountered in military tracked vehicles, helicopters, and high-performance aircraft. This adaptive noise-cancellation filter was developed fo... View full abstract»

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  • A new structure for adaptive linear-phase filtering

    Publication Year: 1987, Page(s):712 - 720
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1160 KB)

    In many applications, including time-varying modeling and adaptive noise canceling, it is desirable to adaptively perform linear-phase filtering to prevent any phase distortion in the observed data. Much attention has been devoted so far to the purely algorithmic aspect of this problem, i.e., how to design an appropriate adaptation algorithm. It is also of interest, however, to measure the extent ... View full abstract»

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  • An alternative adaptive sequential regression algorithm and its application to the recognition of cerebral palsy speech

    Publication Year: 1987, Page(s):782 - 787
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (704 KB)

    An algorithm is presented which can be used to compute a temporally adaptive, recursive solution to the problem of estimating the linear prediction parameters of speech. The method is theoretically equivalent to conventional adaptive sequential regression, but is slightly more efficient and computationally much more straightforward. Application to the problem of recognition of speech of the profou... View full abstract»

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  • Linear recursive adaptive equalization utilizing a modified Gauss - Newton algorithm

    Publication Year: 1987, Page(s):834 - 841
    Cited by:  Papers (1)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (976 KB)

    A new tap update algorithm is developed for linear recursive adaptive equalizers. This algorithm is an extension of the Modified Gauss-Newton algorithm, a least-squares method, which has been successfully used to compute the coefficients for recursive digital filters [13], [19]. The new algorithm is an on-line technique but the taps are updated periodically rather than on a symbol-by-symbol basis.... View full abstract»

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  • Quantization effects in the complex LMS adaptive algorithm: Linearization using dither-theory

    Publication Year: 1987, Page(s):848 - 854
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (816 KB)

    This paper describes the use of dither to linearize the gradient quantizer in a digitally implemented LMS adaptive algorithm. When the LMS algorithm is implemented in a fixed-point digital processor, a choice must be made between rounding the gradient estimate before addition to the contents of the weight accumulator, or rounding the weight at the accumulator output and operating a double-precisio... View full abstract»

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  • Realization of a generalized sidelobe canceller

    Publication Year: 1987, Page(s):759 - 764
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    The use of adaptive multichannel lattice/escalator filters to realize a generalized sidelobe canceller is proposed. This paper studies the performances of the proposed methods and the TDL counterpart via computer simulations for both stationary and nonstationary environments. Experimental results show that the lattice/escalator realizations converge faster and yield smaller mean-square errors than... View full abstract»

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  • Design alternatives for adaptive digital lattice filters and a new bit-serial architecture

    Publication Year: 1987, Page(s):737 - 742
    Cited by:  Papers (7)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    The problem of the efficient realization of an adaptive digital linear prediction filter is investigated, and three implementation approaches are examined: a single-chip general-purpose digital signal processor realization, a multi-chip, multiplexed architecture, and a multichip systolic array approach. In addition, the complete architecture and organization of a systolic-type realization is also ... View full abstract»

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  • System modeling using an adaptive delay filter

    Publication Year: 1987, Page(s):770 - 774
    Cited by:  Papers (30)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (552 KB)

    In this paper, we present a special technique for modeling an unknown system. This technique requires a type of adaptive filter called an Adaptive Delay Filter [1]-[3]. This filter structure includes variable delay taps in addition to variable gains. The Adaptive Delay Filter is especially applicable to system modeling problems in which the system to be modeled has a sparse impulse response [4]-[7... View full abstract»

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  • Median-type filters with adaptive substructures

    Publication Year: 1987, Page(s):842 - 847
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (696 KB)

    In this paper, adaptive filter structures suitable for filtering signals with rapidly varying characteristics are presented. In the proposed Adaptive Median Hybrid (AMH) filters, adaptive filter substructures are used to estimate the current signal value from future signal values and from past input or output signal values. The output of the overall filter is the median of the adaptive filter outp... View full abstract»

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  • Study of a pole - zero adaptive echo canceller

    Publication Year: 1987, Page(s):765 - 769
    Cited by:  Papers (19)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (616 KB)

    The performance of a pole-zero adaptive filter in echo cancellation is studied. Compared with conventional transversal filters, this structure requires fewer taps to achieve the same echo cancellation performance when the echo path can be well modeled by a rational transfer function. Such issues as the degree of echo cancellation, the stability of the filter, the selection of the order, and the ef... View full abstract»

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  • Limited-precision effects in adaptive filtering

    Publication Year: 1987, Page(s):821 - 833
    Cited by:  Papers (157)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1768 KB)

    The effects of limited-precision errors in several popular adaptive-filtering algorithms are analyzed. Performance degradations caused by limited-precision quantization of internal algorithmic quantities are often found to be much larger than what might be otherwise expected. Furthermore, in many cases, limited-precision errors are found to accumulate in time without bound, leading to an eventual ... View full abstract»

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