There are many significant applications of nonlinear adaptive digital filters such as the cancellation of echoes and intersymbol interference, the equalization of transmission channels, adaptive noise cancellation and...
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There are many significant applications of nonlinear adaptive digital filters such as the cancellation of echoes and intersymbol interference, the equalization of transmission channels, adaptive noise cancellation and design of optimal predictors in communication systems. In this paper, we introduce a class of efficient architectures for adaptive quadratic digital filters based on the LMS algorithm and on rank compressed lower-upper (LU) triangular decomposition method. The architectures exhibit high parallelism as well as modularity and regularity. They are mapped into parallel pipeline and systolic array implementations and are evaluated on hardware cost (in bits), and data throughput delay.
The theory of set membership (SM) identification is formulated, and applied to linear prediction (LP) analysis of speech. The LP parameters of a simulated vowel are identified as an illustration. The SM strategy resul...
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The theory of set membership (SM) identification is formulated, and applied to linear prediction (LP) analysis of speech. The LP parameters of a simulated vowel are identified as an illustration. The SM strategy results in a significant computational savings due to rejection of data which are informationless in the SM sense.
A method for recognition of speech of the nonverbal is presented. Results of the application of the procedure to simple utterances by cerebral palsied individuals and implications for an overall communications device ...
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A method for recognition of speech of the nonverbal is presented. Results of the application of the procedure to simple utterances by cerebral palsied individuals and implications for an overall communications device are addressed.
The concept of fast KL transform coding introduced earlier [7], [8] for first-order Markov processes and certain random fields has been extended to higher order autoregressive (AR) sequences and practical images yield...
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The concept of fast KL transform coding introduced earlier [7], [8] for first-order Markov processes and certain random fields has been extended to higher order autoregressive (AR) sequences and practical images yielding what we call recursive block coding (RBC) algorithms. In general, the rate-distortion performance for these algorithms is significantly superior to that of the conventional block KL transform algorithm. Moreover, these algorithms permit the use of small size transforms, thereby removing the need for fast transforms and making the hardware implementation of such coders more appealing. This improved performance has been verified for practical image data and results in suppression of the block-boundary effect commonly observed in traditional transform coding techniques. This is illustrated by comparing RBC with cosine transform coding using both one- and twodimensional algorithms. Examples of RBC encoded images at various rates are given.
Although the magnitude of the discrete Fourier transform of a maximal-length shift-register sequence is flat, except for its value at zero frequency, the higher resolution spectral content given by the Fourier-series ...
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Although the magnitude of the discrete Fourier transform of a maximal-length shift-register sequence is flat, except for its value at zero frequency, the higher resolution spectral content given by the Fourier-series transform is highly erratic. This little-known fact is described, and its ramifications on fast Fourier transforms of one-digit-extended pseudo noise and zero-padded pseudo noise are explained.
The popular class of synchronizers that consist of a quadratic nonlinearity followed by a phase-lock loop is investigated, and it is shown that the optimum design of the quadratic transformation is characterized in te...
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The popular class of synchronizers that consist of a quadratic nonlinearity followed by a phase-lock loop is investigated, and it is shown that the optimum design of the quadratic transformation is characterized in terms of a spectral correlation function for the signal to be synchronized to. It is also shown that the SNR performance of this quadratic transformation, and the mean-square phase jitter of the phaselock loop are both characterized in terms of spectral correlation functions. The conditions under which the optimum quadratic transformations, for symbol synchronization of BPSK, QPSK, SQPSK, and MSK, and for carrier synchronization of BPSK, reduce to the well-known matched-filter-squarer are identified. In addition, the well-known zeromean-square-phase-jitter condition is generalized from PAM to all synchronizable signals, and is characterized in terms of the spectral correlation function. The low-SNR maximum-likelihood synchronizer for all quadratically synchronizable signals is characterized in terms of a multiplicity of maximum-SNR quadratic spectral-line generators. A closed form implementation in terms of a matched filter, squarer, and symbol-rate-synchronized averager is obtained for BPSK and QPSK signals.
This paper discusses the relationship between the zero crossings or zeros of band-limited signals and their nonlinear transformations. It is proved that the bandwidth of a signal can be compressed by a ratio of 1/ n i...
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This paper discusses the relationship between the zero crossings or zeros of band-limited signals and their nonlinear transformations. It is proved that the bandwidth of a signal can be compressed by a ratio of 1/ n if and only if the signal has n th-order zero crossings or zeros (if complex). Also, a monotonic nonlinearity in the observation of a band-limited signal can be identified from the zero crossings (or zeros) of the derivative of the observed signal. (The results are for one-dimensional signals. Extensions to two-dimensional signals remain to be addressed.)
A new algorithm for ray tracing parametric surface patches is presented. The method uses quasi-Newton iteration to solve for the ray/surface intersection and utilizes ray-to-ray coherence by using numerical informatio...
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This paper describes a technique for the enhancement of images by FIR filters which compensates for the decreased response of human vision at high spatial frequencies. Because many images contain mainly horizontal and...
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This paper describes a technique for the enhancement of images by FIR filters which compensates for the decreased response of human vision at high spatial frequencies. Because many images contain mainly horizontal and vertical features, and because vision is less acute along diagonals, it is possible to design anisotropic enhancement filters which do not increase greatly the background noise. The anisotropic design methodology also incorporates other results on filter design based on human vision which have recently been reported by the author and coworkers.
Factor inverse matched filtering (FIMF) and factor inverse filtering (FIF) are signalprocessing techniques used to obtain desired signal responses. Both are especially useful procedures for ‘‘pulse‐compression’’...
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Factor inverse matched filtering (FIMF) and factor inverse filtering (FIF) are signalprocessing techniques used to obtain desired signal responses. Both are especially useful procedures for ‘‘pulse‐compression’’ processing and channel measurements. The theory is developed for a simple channel and known noise power spectral density so that comparison may be made with matched filtering. Expressions for the pulse‐compression energy gain, nonflatness loss NFL, and total performance are derived. The NFL is useful in selecting the best among practical pulse‐compression modulations, and with FIMF and FIF, has been used extensively since 1974 by the authors and their co‐workers in underwater acoustic propagation measurements and ocean acoustictomography.
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