This paper depicts the general analysis before designing optics for an APS based star sensor. The high accuracy requirement and low sensitivity of APS make the optics overcritical. To avoid the extreme difficulty in o...
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ISBN:
(纸本)081945429X
This paper depicts the general analysis before designing optics for an APS based star sensor. The high accuracy requirement and low sensitivity of APS make the optics overcritical. To avoid the extreme difficulty in optics, we abstract the PSF models in sub-pixel scale as the compensation for the distortion error. Both centroid and correlation algorithm are used to determine the spot center. The result of the simulation is presented in the text.
We have proposed a simple correlation algorithm to extract weak distorted fringes buried in both background noise and random noise. The relationship among threshold value, signal to noise ratio and least frame number ...
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We have proposed a simple correlation algorithm to extract weak distorted fringes buried in both background noise and random noise. The relationship among threshold value, signal to noise ratio and least frame number was discussed. The method, is efficiency to measure the shape of an object with low diffuse reflectivity. We have successfully applied the method to measure the shape of a dragonfly wing. (C) 2001 Elsevier Science Ltd. All rights reserved.
Optical triangulation displacement sensors are widely used for their non-contact measurement characteristics, sub-micron order resolution, simple structure, and long operation range. However, errors originating from s...
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ISBN:
(纸本)0819439630
Optical triangulation displacement sensors are widely used for their non-contact measurement characteristics, sub-micron order resolution, simple structure, and long operation range. However, errors originating from surface inclination, speckle effect, light source fluctuation, and detector noise limit the wider use. In order to minimize these errors, the structure for optical triangulation displacement sensors, which is composed of an incoherent source and a linear CCD, has been proposed. But using a linear CCD causes several problems in signal processing. In this paper, we propose an adequate signal processing system for the proposed structure. With the help of the proposed algorithm, the limited resolution problem of CCD can be solved.
Optical triangulation displacement sensors are widely used for their non-contact measurement characteristic, sub-micrometre order resolution, simple structure and long operation range. However. errors originating from...
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Optical triangulation displacement sensors are widely used for their non-contact measurement characteristic, sub-micrometre order resolution, simple structure and long operation range. However. errors originating from surface inclination, speckle effect, light source fluctuation and detector noise restrict the wider use. In order to minimize these errors. a structure for an optical triangulation displacement sensor, which is composed of an incoherent source and a linear CCD (charge coupled device), has been proposed. However. using a linear CCD causes several problems in signal processing. Because CCDs consist of spatially discrete pixels, it is impossible to detect the peak position movement within a pixel. This is an inherently severe problem of CCDs. Therefore, a new approach is needed. In this paper, we propose an adequate signal processing algorithm to overcome the limited resolution problem of a CCD for the proposed sensor structure. The signal processing algorithm is composed of a pre-processing algorithm and a modified cross correlation algorithm. With the help of the proposed algorithm, the limited resolution problem of the CCD can be solved.
In order to solve the double-talk problem in the echo cancelling for teleconference system, the authors have proposed the extended correlation least mean squares (ECLMS) algorithm. However, this algorithm does not giv...
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In order to solve the double-talk problem in the echo cancelling for teleconference system, the authors have proposed the extended correlation least mean squares (ECLMS) algorithm. However, this algorithm does not give a fast convergence. The purpose of this paper is to derive an orthogonal ECLMS (OECLMS) with the lattice structure in order to speed up the convergence characteristics and to reduce the computational load for the adaptation. (C) 2000 IMACS. Published by Elsevier Science B.V. All rights reserved.
A method from the field of chaotic dynamics is applied for the estimation of fractal dimension of images. The method is compared with other well-known algorithms on a set of computer generated images of known fractal ...
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A method from the field of chaotic dynamics is applied for the estimation of fractal dimension of images. The method is compared with other well-known algorithms on a set of computer generated images of known fractal dimension. The results confirm the superiority of the method in terms of accuracy, dynamic range and computational time. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
The applications of the tools of nonlinear time-series analysis to measurements obtained by digital ionosonde ''PARUS,'' created at IZMIRAN, is considered. Small-scale structure of the electron density...
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The applications of the tools of nonlinear time-series analysis to measurements obtained by digital ionosonde ''PARUS,'' created at IZMIRAN, is considered. Small-scale structure of the electron density Ne at F-region of ionosphere is examined by exploring observables of reflected high-frequency radio wave. Time series corresponding to given transmitter frequency f and virtual height h and conforming to usual, not perturbed, day ionogram are examined. Using the standard correlation algorithm, we have determined that for an embedding dimension n=15, computed correlation dimension D2(n) reaches its saturation, D2 congruent to 4. Reliability of the estimation of the correlation dimension was confirmed by applying to our sets of measurements J. Theiler's modification of standard algorithm. The test of time difference, smoothing procedure, calculation of the largest Liapounov exponent, and analysis of the surrogate data were employed in our study of data sets. Although our sets of measurements contain a significant ''random noise'', nonlinear time-series analysis clear up, that the dynamics of unperturbed ionosphere, generating this time series, exhibits low-dimensional behavior.
An algorithm, based on correlation techniques, is proposed for estimating the signal-to-noise ratio of very low frequency signals contaminated by white and flicker noise. Sampling techniques based on converting a sing...
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An algorithm, based on correlation techniques, is proposed for estimating the signal-to-noise ratio of very low frequency signals contaminated by white and flicker noise. Sampling techniques based on converting a single continuous signal into two time series that satisfy the requirements of cross-correlation functions are proposed. The algorithm has been tested on simulated data and the electrocardiogram transduced from ten patients.
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