The well-known uncertainty principle is often invoked in signalprocessing. It is also often considered to have the same implications in signal analysis as does the uncertainty principle in quantum mechanics. The unce...
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ISBN:
(纸本)0819406945
The well-known uncertainty principle is often invoked in signalprocessing. It is also often considered to have the same implications in signal analysis as does the uncertainty principle in quantum mechanics. The uncertainty principle is often incorrectly interpreted to mean that one cannot locate the time-frequency coordinates of a signal with arbitrarily good precision, since, in quantum mechanics, one cannot determine the position and momentum of a particle with arbitrarily good precision. Renyi information of the third order is used to provide an information measure on time-frequency distributions. The results suggest that even though this new measure tracks time-bandwidth results for two Gabor log-ons separated in time and/or frequency, the information measure is more general and provides a quantitative assessment of the number of resolvable components in a time frequency representation. As such, the information measure may be useful as a tool in the design and evaluation of time-frequency distributions.
This paper describes an efficient implementation of auxiliary constraints for a concurrent block least squares adaptive sidelobe canceller when a single array of sensors is used to form one or more main beams. The app...
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ISBN:
(纸本)0819406945
This paper describes an efficient implementation of auxiliary constraints for a concurrent block least squares adaptive sidelobe canceller when a single array of sensors is used to form one or more main beams. The approach is to compute QR decomposition of the auxiliary data matrix and then send this information to main beam processors, where the constraints are applied using a blocking matrix and the individual residuals are computed. The blocking matrix can be chosen with special structure which is used to derive a new fast algorithm and architecture for constrained main beam processing that reduces the operation count from order n3 to order n2, where n is the number of auxiliary sensors.
We compare the performance of three parallel supercomputers executing a bispectrum estimation code used to remove distortions from astronomical data. We discuss the issues in parallelizing the code on an 8-processor s...
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ISBN:
(纸本)0819406945
We compare the performance of three parallel supercomputers executing a bispectrum estimation code used to remove distortions from astronomical data. We discuss the issues in parallelizing the code on an 8-processor shared-memory CRAY Y-MP and a 1024-processor distributed-memory nCUBE machine. Results show that elapsed times on the nCUBE machine are comparable to those on the CRAY Y-MP. Execution of the nCUBE was more than 40 times faster than that of a single processor CRAY-2 resulting in more than 50 times better cost performance. Cost performance on the nCUBE is more than 25 times better than an 8- processor CRAY Y-MP.
A new approach to the problem of detecting the number of signals in unknown colored noise environments is presented. Based on an assumption that the noise is correlated only over a limited spatial range, the principle...
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ISBN:
(纸本)0819406945
A new approach to the problem of detecting the number of signals in unknown colored noise environments is presented. Based on an assumption that the noise is correlated only over a limited spatial range, the principle of canonical correlation analysis is applied to the outputs of two spatially-separated arrays. The number of signals is determined by testing the significance of the sample canonical correlation coefficients. The new method is shown to work well in both white and unknown colored noise situations and does not require any subjective threshold setting. Instead, a set of threshold values are generated according to a specified or desired false alarm rate. Simulation results are included to illustrate the comparative performance of the proposed canonical correlation technique (CCT), versus the well-known AIC and MDL criteria, in colored noise. It is found that the performance of the AIC and MDL criteria degrade very rapidly as the degree of color in the noise increases. On the other hand, the performance of the CCT method is relatively insensitive with respect to variations in degree of color.
A new preconditioner is proposed for the solution of an N × N Toeplitz system TNx = b, where TN can be symmetric indefinite or nonsymmetric, by preconditioned iterative methods. The preconditioner FN is obtained ...
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ISBN:
(纸本)0819406945
A new preconditioner is proposed for the solution of an N × N Toeplitz system TNx = b, where TN can be symmetric indefinite or nonsymmetric, by preconditioned iterative methods. The preconditioner FN is obtained based on factorizing the generating function T(z) into the product of two terms corresponding, respectively, to minimum-phase causal and anticausal systems and therefore called the minimum-phase LU (MPLU) factorization preconditioner. Due to the minimum-phase property, F N-1 is bounded. For rational Toeplitz TN with generating function T(z) = A(z-1)/B(z-1) + C(z)/D(z), where A(z), B(z), C(z), and D(z) are polynomials of orders p1, q1, p2, and q2, we show that the eigenvalues of FN-1TN are repeated exactly at 1 except at most α F outliers, where αF depends on p1, q1, p2, q2, and the number approximately ega of the roots of T(z) = A(z-1)D(z) + B(z-1)C(z) outside the unit circle. A preconditioner KN in circulant form generalized from the symmetric case is also presented for comparison.
A general solution for the problem of time-frequency signal representation of nonlinear FM signals is provided, based on a generalization of the Wigner-Ville distribution. The Wigner-Ville distribution (WVD) is a seco...
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ISBN:
(纸本)0819406945
A general solution for the problem of time-frequency signal representation of nonlinear FM signals is provided, based on a generalization of the Wigner-Ville distribution. The Wigner-Ville distribution (WVD) is a second order time-frequency representation. That is, it is able to give ideal energy concentration for quadratic phase signals and its ensemble average is a second order time-varying spectrum. The same holds for Cohen's class of time-frequency distributions, which are smoothed versions of the WVD. The WVD may be extended so as to achieve ideal energy concentration for higher order phase laws, and such that the expectation is a time-varying higher order spectrum. The usefulness of these generalized Wigner-Ville distributions (GWVD) is twofold. Firstly, because they achieve ideal energy concentration for polynomial phase signals, they may be used for optimal instantaneous frequency estimation. Second, they are useful for discriminating between nonstationary processes of differing higher order moments. In the same way that the WVD is generalized, we generalize Cohen's class of TFDs by defining a class of generalized time-frequency distributions (GTFDs) obtained by a two dimensional smoothing of the GWVD. Another results derived from this approach is a method based on higher order spectra which allows the separation of cross-terms and auto- terms in the WVD.
The proceedings contains 49 papers. The papers are grouped under following session headings: signalprocessing techniques;nonlinear signalprocessing and neural networks;time-frequency distribution and nostationary si...
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The proceedings contains 49 papers. The papers are grouped under following session headings: signalprocessing techniques;nonlinear signalprocessing and neural networks;time-frequency distribution and nostationary signals;wavelets and wideband ambiguity functions;matrix computations;and real-time implementations. Some of the specific topics discussed are;wavelets and related time-scale transforms;adaptive lattice bilinear filters;optimal kernels for time-frequency analysis;applications of fast wavelet transform;and updating signal subspaces.
The proceedings contain 49 papers. The topic discussed include: wavelets and related time-scale transforms;tomographic techniques in image and signalprocessing;higher-order statistics (spectra) and their application ...
The proceedings contain 49 papers. The topic discussed include: wavelets and related time-scale transforms;tomographic techniques in image and signalprocessing;higher-order statistics (spectra) and their application in signalprocessing;real-time SAR change-detection using neural networks;nonlinear signalprocessing using radial basis functions;nonlinear classification and adaptive structures;global search of adaptive IIR filter error surfaces using stochastic learning automata;direction finding using a modified minimum-eigenvector technique;and translation, rotation, and scaling invariant object and texture classification using polyspectra.
An iterative solution is given for solving deblurring problems having nonnegativity constraints through the use of methods motivated by tomographic imaging.
ISBN:
(纸本)0819404098
An iterative solution is given for solving deblurring problems having nonnegativity constraints through the use of methods motivated by tomographic imaging.
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