In certain applications, the discretization of two-dimensional integral equations can lead to systems involving matrices with block Toeplitz-Toeplitz block structure. Iterative Krylov subspace methods are sometimes em...
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ISBN:
(纸本)0819429163
In certain applications, the discretization of two-dimensional integral equations can lead to systems involving matrices with block Toeplitz-Toeplitz block structure. Iterative Krylov subspace methods are sometimes employed to find regularized solutions to the related 2D discrete ill-posed problems;however, preconditioners which filter noise are needed to speed convergence to regularized solutions. We describe a preconditioning technique based on the Toeplitz-type structure of the matrix which generalizes the approaches in [1] and [2] to take advantage of symmetry and real arithmetic operations. We use fast sine transforms to transform the original system to a system whose matrix has partially reconstructible Cauchy-like blocks. The preconditioner is a block diagonal, rank m approximation to this matrix, with Cauchy-like blocks each augmented by an identity of appropriate dimension. We note that the initialization cost is in general less than that for the similar 2D preconditioner in [2] which does not take advantage of symmetry. Several examples are given which illustrate the success of our preconditioned methods.
The problem of blind equalization of MIMO (multiple-input nultiple-output) communications channels is considered using the second-order statistics of the data. Such models arise when a single receiver data from multip...
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ISBN:
(纸本)0819429163
The problem of blind equalization of MIMO (multiple-input nultiple-output) communications channels is considered using the second-order statistics of the data. Such models arise when a single receiver data from multiple sources is fractionally sampled (assuming that there is excess bandwidth), or when an antenna array is used with or without fractional sampling. We focus on direct design of finite-length MMSE (minimum mean-square error) blind equalizers. We allow infinite impulse response (IIR) channels. Our approaches also work when the "subchannel" transfer functions have common zeros so long as the common zeros are minimum-phase zeros. We only require that the there exist a causal, stable left inverse (not necessarily unique) to the MIMO transfer function and that the leading coefficient matrix of the MIMO channel impulse response have its rank equal to the number of sources. The channel length or model orders need not be known. The sources are recovered up to a unitary mixing matrix and are further 'unmixed' using higher-order statistics of the data. An illustrative simulation example is provided.
An innovative approach is being used to implement and simulate the infrared (IR) and laser radar signalprocessingalgorithms for the advanced Sensor Technology Program (ASTP) and the Discrimination Interceptor Techno...
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ISBN:
(纸本)0819428221
An innovative approach is being used to implement and simulate the infrared (IR) and laser radar signalprocessingalgorithms for the advanced Sensor Technology Program (ASTP) and the Discrimination Interceptor Technology Program (DITP). Although the algorithms will run on four different computer architectures, they will use the same source code for all implementations. The initial development and testing will occur in Mathcad on a Windows 95/NT personal computer, then move to simulation on a Silicon Graphics (SGI) workstation, then to scaled real-time simulation on a parallel high performance computer (HPC), and finally to the actual flight processor, the miniaturized parallel Wafer Scale signal Processor (WSSP) with a MIMD (multiple-instruction and multiple data) architecture. This flexibility is accomplished with code wrappers that implement interchangeable interface layers for the code modules, one wrapper for Mathcad matrices, one for C++ objects on the workstation, one for message passing with static routing on the HPC, and one for dynamically routed message passing on the WSSP. With this approach, developers can move modules back and forth from the workstation simulation environment to the implementation hardware. This will eliminate the need to maintain different versions of the same algorithm. The signalprocessingalgorithms will be modified to work in a massively parallel architecture, with a message passing interface, which is simulated on the Silicon Graphics workstation, emulated on the HPC, and implemented on the WSSP. This approach will allow for pipeline processing as well as multiple, concurrently running instances of modules. In addition, innovative algorithms will fuse active laser radar detections and passive multicolor IR sensor measurements to improve target state estimation.
We calculate the instantaneous frequency at a fixed position of a propagating pulse in the asymptotic regime. We also discuss the multimode case and relate it to the concept of instantaneous bandwidth.
ISBN:
(纸本)0819425842
We calculate the instantaneous frequency at a fixed position of a propagating pulse in the asymptotic regime. We also discuss the multimode case and relate it to the concept of instantaneous bandwidth.
Impulsive transient signals have been difficult to characterize and classify using traditional signalprocessing methods. We show that time-frequency distributions can effectively characterize the transient response o...
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ISBN:
(纸本)0819425842
Impulsive transient signals have been difficult to characterize and classify using traditional signalprocessing methods. We show that time-frequency distributions can effectively characterize the transient response of an acoustical cavity. Class-dependent kernels developed from time-frequency distributions are used to successfully classify the impulsive transients.
This paper presents, Index Mapping, a technique to efficiently map a widely used class of digital signalprocessingalgorithms onto a space/time paradigm with immediate representation as the partitioning and schedulin...
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ISBN:
(纸本)0819425842
This paper presents, Index Mapping, a technique to efficiently map a widely used class of digital signalprocessingalgorithms onto a space/time paradigm with immediate representation as the partitioning and scheduling map of a small, I/O efficient, hardware array. When applied to reconfigurable FPGA based hardware architectures with downstream Sea-of-Gates optimization methods, the resulting systems form a dynamic signalprocessing environment with the best mix of performance and flexibility for wireless applications. Herein, Index Mapping is demonstrated with a mapping of the Fast Fourier Transform (FFT) onto an FPGA computing machine, the ReConfigurable Processor (RCP).
In this paper a novel method of estimating displacement of moving objects from one frame to the next in the image sequence is presented. This method is based on using the artificial neural networks for different model...
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ISBN:
(纸本)0819425842
In this paper a novel method of estimating displacement of moving objects from one frame to the next in the image sequence is presented. This method is based on using the artificial neural networks for different models of motion. The two model is examined: affine flow and planar surface motion. Various circuit architectures of simple neuron-like processors are considered for estimation of motion parameters. The efficiency of the proposed networks are investigated by computer simulation for using in video processing.
We discuss applications of time-frequency analysis to the investigation of astronomical type signals. In particular, we apply time-frequency techniques to a data set consisting of the kinetic energy in the three body ...
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ISBN:
(纸本)0819425842
We discuss applications of time-frequency analysis to the investigation of astronomical type signals. In particular, we apply time-frequency techniques to a data set consisting of the kinetic energy in the three body problem We explain how the methods of time-frequency analysis shed light on these signals and also how the concept of multicomponent signals is applied to their decomposition. We also discuss methods to do simple filtering and estimation of the signal parameters.
This paper considers ''blind beamforming'' operations on a wireless network of randomly distributed MEM sensors. Maximum power collection criterion is proposed and results in array weights obtained fro...
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ISBN:
(纸本)0819425842
This paper considers ''blind beamforming'' operations on a wireless network of randomly distributed MEM sensors. Maximum power collection criterion is proposed and results in array weights obtained from the eigenvector corresponding to largest eigenvalue of a matrix eigenvalue problem. Theoretical justification of this approach to an extension of Szego's asymptotic distribution of eigenvalues is provided. Numerical results on propagation time delay estimation and loss of coherency due to propagation disturbances are presented.
The proceeding contains 53 papers from the conference of SPIE advanced VIII signalprocessing: algorithms, architectures, and implementations. The topics:include pattern recognition under translation and scale changes...
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The proceeding contains 53 papers from the conference of SPIE advanced VIII signalprocessing: algorithms, architectures, and implementations. The topics:include pattern recognition under translation and scale changes, instanteous frequency of a propagating pulse;data-driven time-frequency and time-scale detectors;time-varying frequencies of a signal;circulant preconditioners from B-splines;extensions to total variation denoising and Jacobi method for signal subspace computation.
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