作者：
Rohrbaugh, RUSN
CTR SURFACE WARFAREADV SIGNAL PROC BRANCHBREMERTONWA 98314
Time-frequency methods are applied for bearing analysis of a motor-generator. We show that these methods reveal features that are not seen by traditional methods, such as the power spectrum. These features may be used...
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ISBN:
(纸本)0819422347
Time-frequency methods are applied for bearing analysis of a motor-generator. We show that these methods reveal features that are not seen by traditional methods, such as the power spectrum. These features may be used for detection of specific faults and as supplemental information to assess the condition of the machine.
An on-chip VLSI architecture for computation of Fourier transforms is presented. It performs the arithmetic operations in a digit-level pipeline fashion. For this purpose, the implementation of arithmetic operators is...
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ISBN:
(纸本)0819412767
An on-chip VLSI architecture for computation of Fourier transforms is presented. It performs the arithmetic operations in a digit-level pipeline fashion. For this purpose, the implementation of arithmetic operators is based on on-line (i.e., digit-serial and most significant digit first) arithmetic, and the transforms are performed by a parallel-pipeline version of the Cooley- Tukey fast Fourier transform (FFT) algorithm.
This paper illustrates a vehicle imaging technique for ground traffic control applications. The imaging is performed by exploiting the vehicle motion with respect to a pair of linear arrays. The method for estimating ...
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ISBN:
(纸本)0819412767
This paper illustrates a vehicle imaging technique for ground traffic control applications. The imaging is performed by exploiting the vehicle motion with respect to a pair of linear arrays. The method for estimating the vehicular velocity from the data collected by one of the arrays is described, and the theoretical accuracy of the estimate is discussed in detail through the evaluation of the Rao-Cramer bound. In particular it is recognized that the maximum likelihood solution is based on the radon transform of the data. Experimental results obtained with a field operating prototype are finally shown.
This paper derives the relationship between the coefficients of the Fourier expansion of a periodic signal and the coefficients of the wavelet expansion of the same signal. The formula derived shows how the Fourier co...
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ISBN:
(纸本)0819404098
This paper derives the relationship between the coefficients of the Fourier expansion of a periodic signal and the coefficients of the wavelet expansion of the same signal. The formula derived shows how the Fourier concept of frequency and the wavelet concept of scale are related and how the wavelet coefficients display the information contained in the signal in a new way. The relationship also shows how the wavelet expansion can be used to approximately calculate the Fourier coefficients.
A new approach for signal extrapolation based on wavelet representation known as scale-time limited extrapolation and a denoising process is investigated in this research. We first examine a new signal modeling techni...
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ISBN:
(纸本)0819412767
A new approach for signal extrapolation based on wavelet representation known as scale-time limited extrapolation and a denoising process is investigated in this research. We first examine a new signal modeling technique using wavelets and the corresponding scale-time limited signal extrapolation algorithm. Then, the sensitivity of the algorithm to noise is discussed, and a denoising algorithm based on the time-localization property of the wavelet transform is proposed. By integrating the denoising process and the iterative scale-time limited extrapolation algorithm, we obtain a very robust signal extrapolation algorithm for noisy data. A simulation result of signal extrapolation from noisy observed data is presented to illustrate the performance of the proposed robust signal extrapolation algorithm.
We review, recent work on defining the time-frequency moments of a signal. Expressions are given for moments dropt(m)drop(omega), and of all orders n, m, in terms of the amplitude and phase of the signal and spectrum....
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ISBN:
(纸本)0819441880
We review, recent work on defining the time-frequency moments of a signal. Expressions are given for moments dropt(m)drop(omega), and of all orders n, m, in terms of the amplitude and phase of the signal and spectrum. Knowing the time-frequency moments is of interest for a variety of reasons. including their potential utility as features for classification of nonstationary signals, and also because from the moments one call construct the time-varying spectral density, or approximate it using a few moments.
Beam-based adaptive processing is an economical way to achieve good interference rejection performance from an adaptive receiving array, at much less computational cost than full element-based methods. However, to exp...
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ISBN:
(纸本)0819404098
Beam-based adaptive processing is an economical way to achieve good interference rejection performance from an adaptive receiving array, at much less computational cost than full element-based methods. However, to exploit this potential for planar arrays it is necessary to identify, in real time, which beams must be retained for adaptive concellation. This paper analyzes the beam-selection problem and presents a computationally efficient algorithm that performs real-time beam selection.
We show that for purely frequency modulated signals one can always find a distribution which is infinitely concentrated along its instantaneous frequency. For signals that are both frequency and amplitude modulated we...
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ISBN:
(纸本)0819404098
We show that for purely frequency modulated signals one can always find a distribution which is infinitely concentrated along its instantaneous frequency. For signals that are both frequency and amplitude modulated we consider a class of distribution which are explicit functionals of the instantaneous frequency. lated
We consider dispersive propagation with damping in phase-space, and derive the Wigner distribution in terms of the initial wave and the dispersion relation. The case for no damping. that is. lossless propagation, has ...
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ISBN:
(纸本)0819454974
We consider dispersive propagation with damping in phase-space, and derive the Wigner distribution in terms of the initial wave and the dispersion relation. The case for no damping. that is. lossless propagation, has been previously considered by Cohen, and is a special case of the more general result presented here. Simple and physically revealing approximations of the Wigner distribution in terms of the initial Wigner distribution are presented. Also. exact low-order conditional moments are given and their interpretation is discussed.
Searching for wideband short duration chirps is an important issue in spectrum surveillance. We propose a method and apparatus, inspired by optical tomography, by which a one-dimensional signal is converted to a two-d...
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ISBN:
(纸本)0819429163
Searching for wideband short duration chirps is an important issue in spectrum surveillance. We propose a method and apparatus, inspired by optical tomography, by which a one-dimensional signal is converted to a two-dimensional image. This image has the remarkable property that it may disclose discernible structure. A chirp in additive white Gaussian noise, even undersampled, may be detected. The process is inherently linear and may be easily implemented by parallel processing or through the construction of an optoelectronic device.
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