Images in real life are inhomogeneous while the transmission channels are time varying, hence, adaptive schemes are suitable for tracking slow variations on system identification and inverse filtering. In this paper w...
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A computationally efficient identification procedure is proposed for a nonGaussian white-noise-driven linear, time-invariant, nonminimum phase system. The method is based on the idea of computing the complex cepstrum ...
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A computationally efficient identification procedure is proposed for a nonGaussian white-noise-driven linear, time-invariant, nonminimum phase system. The method is based on the idea of computing the complex cepstrum of higher order cumulants of the system output. In particular, the differential cepstrum parameters of the nonminimum phase impulse response are estimated directly from higher-order cumulants by least-squares solution or two-dimensional FFT operations. The method reconstructs the minimum-phase and maximum-phase impulse response components separately. It is flexible enough to be applied on autoregressive (AR), moving average (MA), or ARMA system without a priori knowledge of the type of the system. Benchmark simulation examples demonstrate the effectiveness of the method even with short length data records.< >
A speech model with an excitation that is a multipulse sequence with additive white noise is presented. This model, when used in a 4.8-kb/s communication system, has the potential for improved synthetic speech quality...
A speech model with an excitation that is a multipulse sequence with additive white noise is presented. This model, when used in a 4.8-kb/s communication system, has the potential for improved synthetic speech quality. The algorithm is described and convergence for synthetic data of the assumed structure is proved. A method for significantly improved efficiency is presented, based on an algorithm given by M. Korenberg (1985). Initial experimental data that support both the authors' and Korenberg algorithms are given.< >
Simple analog functions such as mixing and editing often have complex implementations in the digital domain. Previous machines designed expressly for such tasks, such as the Lucasfilm ASP and Neve BBC machine, are hea...
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Simple analog functions such as mixing and editing often have complex implementations in the digital domain. Previous machines designed expressly for such tasks, such as the Lucasfilm ASP and Neve BBC machine, are heavily pipelined and complex machines with extremely fast cycle times. The author describes the hardware architecture of a MIMD (multi-instruction/multiple-data-stream) multiprocessor designed to handle the problems of high-quality digital audio mixing, synthesis, and editing.< >
Signed-digit (SD) arithmetic techniques are evaluated for applicability to DSP (digital signal-processing) architectures used for high-speed applications. Binary number representations limit the speed of the system du...
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Signed-digit (SD) arithmetic techniques are evaluated for applicability to DSP (digital signal-processing) architectures used for high-speed applications. Binary number representations limit the speed of the system due to carry propagation in addition, Residue arithmetic has been tried to alleviate this problem but its use introduces other problems in algebraic comparison, conversion, division, and floating-point representation. It is shown that signed-digit arithmetic offers the advantage of parallelism in computation without the problems associated with the residue number system. An overview of the basic features of SD arithmetic is given, followed by structures for primitive operations required for a general-purpose signal processor.< >
In adaptive IIR filtering, the gradient search techniques such as LMS, SER, etc., minimize the mean square output error (MSOE). The uniqueness of the minimum MSOE estimate for exactly matching adaptive filters is a ne...
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In adaptive IIR filtering, the gradient search techniques such as LMS, SER, etc., minimize the mean square output error (MSOE). The uniqueness of the minimum MSOE estimate for exactly matching adaptive filters is a necessary condition for possible global convergence of these algorithms. This uniqueness is guaranteed if Soderstrom's condition, n/sub b/-n/sub c/+1/spl ges/0, is met when the input is white. Here, we introduce a weaker sufficient condition for uninmodality of MSOE surfaces associated with exactly matching adaptive IIR filter. This is accomplished by manipulation of certain cross-correlation matrix of low order systems, and by generalization of the result to higher order systems, The result is then applied to some existing examples in the literature.
A multihop packet radio network using receiver-directed code-division multiple access (CDMA) is considered. The network is modeled as a system of interacting queues, and sufficient conditions for the stability of the ...
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A multihop packet radio network using receiver-directed code-division multiple access (CDMA) is considered. The network is modeled as a system of interacting queues, and sufficient conditions for the stability of the queueing system model are obtained. Under an independence assumption, approximate results for the mean packet delay in a symmetric network are given. The results are used to characterize the throughput-delay performance of a symmetric network using frequency-hop spread-spectrum signalling.< >
The general order, multichannel FTF algorithm is a generalization of the multichannel FTF algorithm in which the orders of the input channels can be independently specified. The algorithm is applied to a special case ...
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The general order, multichannel FTF algorithm is a generalization of the multichannel FTF algorithm in which the orders of the input channels can be independently specified. The algorithm is applied to a special case of a two-input-channel, joint process estimator. One of the input channels is defined as the unit-delayed joint process signal; the configuration is an 'equation error' form for least squares (LS) pole-zero ARMA (autoregressive moving-average) system identification. This form is also used in decision-directed equalization and echo cancellation. For this special two-channel case, a computational savings of 2N+1 operations per recursive update is identified, where N is the total number of filter taps. The saving is proven using the concepts of projection onto a vector space. The reduction is available with any of the order-N 'fast' LS algorithms including the fast Kalman (FK) and FAEST algorithms; this had not been recognized for similar application of the FK algorithm to decision-directed equalization. A summary of the modified algorithm is given, with an operations count for each step.< >
A second-order Delta Sigma modulator is analyzed using linearized gains to model the nonlinearities associated both with the comparator and with the saturation of the integrators. A set of nine equations in nine unkno...
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A second-order Delta Sigma modulator is analyzed using linearized gains to model the nonlinearities associated both with the comparator and with the saturation of the integrators. A set of nine equations in nine unknowns is derived for this model. Simulations results are presented that show that saturation of the integrators can actually increase the SNR.< >
The authors describe the design, operation, and capabilities of CAPSIM (capture and simulate), a complete interactive simulation environment for design and analysis of communication systems. The integrated environment...
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The authors describe the design, operation, and capabilities of CAPSIM (capture and simulate), a complete interactive simulation environment for design and analysis of communication systems. The integrated environment includes the capability to design models, subsystems, and systems in a hierarchical fashion using block diagrams (icons), configure and execute a simulation; review the results of the simulation; and perform design iterations. Each of these capabilities is controlled through a consistent user interface utilizing interactive graphics. Use of icons, popup menus, and a mouse makes simulation entry simple and rapid. Recent advances in software engineering, workstation technology and CAD/CAM (computer-aided design/computer-aid manufacturing) techniques are incorporated in CAPSIM to provide an intelligent, user-friendly and flexible state-of-the-art simulation environment.< >
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