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.
Information processing theory aims to quantify, how well signals encode information and how well systems process information. Time-frequency distributions have been used to represent the energy distribution of time-va...
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ISBN:
(纸本)0819454974
Information processing theory aims to quantify, how well signals encode information and how well systems process information. Time-frequency distributions have been used to represent the energy distribution of time-varying signals for the past twenty years. There has been a lot of research on various properties of these representations. However, there is a general lack of quantitative analysis in describing the amount of information encoded into a time-frequency distribution. This paper aims to quantify how well time-frequency distributions represent information by using information-theoretic distance measures. Different distance measures, such as Kullback-Leibler distance, Renyi distance, will be adapted to the time-frequency plane. Their performance in quantifying the information in a given signal will be compared. A sensitivity analysis for different distance measures will be carried out to assess their robustness under perturbation. Different example signals will be considered for illustrating the information processing in time-frequency distributions.
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.
Media signalprocessing requires high computing power and the algorithms exhibit a great deal of parallelism on low precision data. The basic components of multi-media objects are usually simple integers with 8, 12, o...
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ISBN:
(纸本)0819437611
Media signalprocessing requires high computing power and the algorithms exhibit a great deal of parallelism on low precision data. The basic components of multi-media objects are usually simple integers with 8, 12, or 16 bits of precision. In order to support efficient processing of media signals, Instructions Set Architecture (ISA) of the traditional processors requires modifications. In this paper, we present the quantitative analysis and the computational complexity required to perform media processing. Main classes of instructions that are needed for the required level of performance of the Media Processor are identified. Their efficient implementation and effect on the processor data-path is discussed. The main operations required in media processing are Addition (with or without saturation), Multiplication (with or without rounding), Sum of Products, and Average of two numbers.
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.
In this paper we introduce a. multi-scale deconvolution technique performed in the scale-domain. In sensor array applications such as in radar, sonar and seismic processing, the sensor outputs are modeled as the convo...
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ISBN:
(纸本)0819432938
In this paper we introduce a. multi-scale deconvolution technique performed in the scale-domain. In sensor array applications such as in radar, sonar and seismic processing, the sensor outputs are modeled as the convolution of the unknown source signal with various unknown system impulse responses that are scaled versions of each other with unknown scale parameters. In many applications these signals or the scaling parameters are needed to be estimated only from the sensor outputs. In our earlier work, we estimated the unknown scale parameters by using properties of the scale transform and then employed existing deconvolution algorithms. Here, we derive the multiscale blind deconvolution algorithm in the scale transform domain. The performance of the method is illustrated using simulation examples.
This conference proceedings contains 39 papers. The topics discussed are algorithmic engineering, algorithm implementations, parallel processing systems, pipeline processing systems, signalprocessingarchitectures, a...
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ISBN:
(纸本)081940943X
This conference proceedings contains 39 papers. The topics discussed are algorithmic engineering, algorithm implementations, parallel processing systems, pipeline processing systems, signalprocessingarchitectures, array processing and direction finding, time frequency signal analysis, higher-order spectra, signal theory, wavelets, and time-frequency distributions.
The proceedings contains 56 papers from the conference on SPIE: advancedsignalprocessingalgorithms, architectures, and implementations XI. The topics discussed include: modulation frequency and efficient audio codi...
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The proceedings contains 56 papers from the conference on SPIE: advancedsignalprocessingalgorithms, architectures, and implementations XI. The topics discussed include: modulation frequency and efficient audio coding;application of wavelet- and wavelet-packet-transform to human skin data;Wigner distribution and pulse propagation;time-frequency analysis using sidelobe apodization;spectral phase algorithm for detecting and estimating pitch;and minimum entropy approach to denoising time-frequency distributions.
We present a general procedure for obtaining equations of motion for the Wigner distribution of functions that are governed by ordinary and partial differential equations. For the case of fields we show that in genera...
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ISBN:
(纸本)0819437611
We present a general procedure for obtaining equations of motion for the Wigner distribution of functions that are governed by ordinary and partial differential equations. For the case of fields we show that in general one must consider Wigner distributions of the four variables, position, momentum, time and frequency. We also show that in general one cannot write an equation of motion for position and momentum however it can be done in some cases, the Schrodinger equation being one such case. Our method leads to an equation of motion for the Schrodinger equation with time dependent potentials in contrast to the result obtained by Wigner and Moyal which was for time independent potentials.
We argue that the standard definition of signal to noise ratio may be misleading when the signal or noise are nonstationary. We introduce a new measure that we call local signal to noise ratio (LSNR) which is well sui...
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ISBN:
(纸本)0819463922
We argue that the standard definition of signal to noise ratio may be misleading when the signal or noise are nonstationary. We introduce a new measure that we call local signal to noise ratio (LSNR) which is well suited to take into account nonstationary situations. The advantage of our measure is that it is a local property unlike the standard SNR which is a single number representing the total duration of the signal. We simulated a number of cases to show that our measure is more indicative of the noise and signal level for nonstationary situations.
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