This Volume 5205 of the conference proceedings contains 59 papers. Topics discussed include time frequency and time scale analysis, adaptive sensor network, wireless communication, image processing, exploitation of st...
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This Volume 5205 of the conference proceedings contains 59 papers. Topics discussed include time frequency and time scale analysis, adaptive sensor network, wireless communication, image processing, exploitation of structured in imaging and signalprocessing, matrix algorithms, signalprocessing applications, computer arithmetic and arithmetic and architectures for real time applications.
This paper is devoted to change detection for precision agriculture. It presents a new change detection methodology and an overview of an online image processing tool (***) with direct applicability for crop classific...
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ISBN:
(纸本)0819450782
This paper is devoted to change detection for precision agriculture. It presents a new change detection methodology and an overview of an online image processing tool (***) with direct applicability for crop classification. The change detection algorithms discussed in the paper will be implemented on the web. They preserve the fine details of the pixel changes and furthermore may be used for crop classification. Image registration, calibration/normalization, pixel level transformations, clutter suppression and pixel level change detection are discussed and new technologies are presented. The effectiveness of the proposed technology is being tested on real SAR data with partial truthing.
Preconditioning techniques for linear systems are widely used in order to speed up the convergence of iterative methods. Unfortunately, linear systems arising in image processing are highly ill-conditioned and precond...
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ISBN:
(纸本)0819450782
Preconditioning techniques for linear systems are widely used in order to speed up the convergence of iterative methods. Unfortunately, linear systems arising in image processing are highly ill-conditioned and preconditioners often give bad results, since the noise components on the data are strongly amplified already at the early iterations. In this work, we propose filtering strategies which allow to obtain preconditioners with regularization features for Toeplitz systems of image deblurring. Regularization preconditioners are able to speed up the convergence in the space less sensitive to the noise and, simultaneously, they slow down the restoration from components mainly corrupted by noise. A 2-d numerical simulation concerning astronomical image deblurring confirms the effectiveness of the arguments.
Inter-symbol interference (ISI) and co-channel interference (CCI) are two major sources to signal impairment in mobile communications. To suppress both ISI and CCI, space-time adaptive processing (STAP) systems are sh...
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ISBN:
(纸本)0819450782
Inter-symbol interference (ISI) and co-channel interference (CCI) are two major sources to signal impairment in mobile communications. To suppress both ISI and CCI, space-time adaptive processing (STAP) systems are shown to be effective, leading to increased capacity and improved quality of service. The high complexity and slow convergence, however, are often the hurdles in practical implementation of the STAP systems. Several subband array implementations have been proposed for STAP over the past a few years. These methods are to provide optimal or sub-optimal steady state performance with reduced implementation complexity and improved convergence performance. The purpose of this paper is to investigate the steady state performance of subband arrays with different decimation rates and to derive analytical expressions of the minimum mean square error (MMSE). The discrete Fourier transform (DFT) based subband arrays and both unconstrained and constrained weight adaptations are considered.
A comprehensive theory for time-frequency based signal detection has been developed during the past decade. The time-frequency detectors proposed in literature are linear structures operating on the time-frequency rep...
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ISBN:
(纸本)0819450782
A comprehensive theory for time-frequency based signal detection has been developed during the past decade. The time-frequency detectors proposed in literature are linear structures operating on the time-frequency representation of the signals and are equivalent to quadratic receivers that are defined in the,time domain. In this paper, an information theoretic approach for signal detection on the time-frequency plane is introduced. In recent years, Renyi entropy has been proposed as an effective measure for quantifying signal complexity on the time-frequency plane and some important properties of this measure have been proven. In this paper, a new approach that uses the entropy functional as the test statistic for signal detection is developed. The minimum error detection algorithm is derived and the performance of this new signal detection method is demonstrated through examples.
We introduce a new space-time signalprocessing scheme that uses both transmitter diversity technique and beamforming technique for code-division multiple access (CDMA) systems. The introduced scheme achieves the dive...
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ISBN:
(纸本)0819450782
We introduce a new space-time signalprocessing scheme that uses both transmitter diversity technique and beamforming technique for code-division multiple access (CDMA) systems. The introduced scheme achieves the diversity gain over Rayleigh fading channel through the transmitter diversity technique, and the signal-to-noise ratio (SNR) gain by the beamforming technique. Bit error rate (BER) analyses are given each of the three cases in which the transmitter diversity, beamforming and introduced combined scheme are used, in the frequency-flat Rayleigh fading channel. The analytic results are shown to coincide with the Monte-Carlo simulation results. We show that the combined scheme is more robust to the channel correlation and the speed of mobile than the diversity and beamforming scheme. Furthermore, the combined scheme gives a reduced multiple-access-interference because of its beamforming capability.
作者:
Hughes, DHUSAF
Res Lab Ctr Integrated Transmiss & Exploitat Rome NY 13441 USA
A femtosecond electromagnetic pulse propagating in a linear dispersive medium is analyzed in phase spaces of (space, wave number) and (time, frequency). First moment densities are computed as eigenvalues of differenti...
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ISBN:
(纸本)0819450782
A femtosecond electromagnetic pulse propagating in a linear dispersive medium is analyzed in phase spaces of (space, wave number) and (time, frequency). First moment densities are computed as eigenvalues of differential operators acting on Hilbert ray representations of the pulse in relevant domains. These moment densities are used as metrics in the relevant phase spaces to measure the local mean values and their deviations in position and wavenumber, and in time and frequency. For example, arrival times of the pulse over its spectral content are computed as the mean arrival time at a particular frequency to within one half the local deviation at that frequency. These metrics on the pulse are compared to the relevant phase space Wigner distribution.
The problem of kernel design for Cohen time-frequency distributions is formulated as a blind deconvolution problem. It is shown that the iterative blind deconvolution method (IBDM) used in image restoration problems c...
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ISBN:
(纸本)0819450782
The problem of kernel design for Cohen time-frequency distributions is formulated as a blind deconvolution problem. It is shown that the iterative blind deconvolution method (IBDM) used in image restoration problems can be successfully applied to solve the kernel design problem. We obtain the following results: (1) the rate of convergence depends on which domains the constraints are imposed (2) certain constraints are needed for algorithm convergence (3) the more constrained the kernel design is, the faster the rate of convergence (4) there are tradeoffs between constraints, e.g., compact support vs. satisfaction of marginals;(5) time-frequency distributions which are more amenable to visual interpretation can be obtained using this algorithm.
We address the question of the importance of satisfying the marginal conditions in a time-frequency distribution and discuss in detail the fundamental and practical issues involved. We also examine the marginals of th...
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ISBN:
(纸本)0819450782
We address the question of the importance of satisfying the marginal conditions in a time-frequency distribution and discuss in detail the fundamental and practical issues involved. We also examine the marginals of the spectrogram. The spectrogram often gives reasonable results even though both marginals can never be satisfied exactly, but sometimes it can give very unreasonable results. We show by examples that the spectrogram gives the clearest characterization of the time-frequency properties of a signal when the combined error in both of its marginals is as small as possible. In contrast, when the error in either one of the marginals of the spectrogram is large, the time-frequency characterization degrades. Some different error measures are described. We discuss the issues involved both theoretically and by way of numerical simulations. We also address the issue of marginals for the random case.
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