The Experts below are selected from a list of 31920 Experts worldwide ranked by ideXlab platform
Yong Wang - One of the best experts on this subject based on the ideXlab platform.
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The Study on Non-Line-of-Sight Ultraviolet Communication System in the Atmospheric Turbulence
Applied Mechanics and Materials, 2014Co-Authors: Yong WangAbstract:In the Atmospheric Turbulence, the effects of Atmospheric Turbulence and transmitted optical power on the BER performance of ultraviolet communication system are analyzed and simulated. The simulation results show that when the Atmospheric Turbulence strength changes from weak to strong, the BER performance deteriorates along. Compared to OOK intensity modulation, the BPSK subcarrier intensity modulation can be more effectively to inhibit Atmospheric Turbulence effect on ultraviolet communication system. Under the certain Atmospheric Turbulence strength, the BER performance of ultraviolet communication system will be improved along with the increase of the transmitted optical power.
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Analysis on the Effects of Atmospheric Turbulence on Line-of-Sight Ultraviolet Communication System Performance
Advanced Materials Research, 2014Co-Authors: Yong WangAbstract:In the ultraviolet communication system, optical signals being transmitted are not only attenuated in energy, but also affected by the Atmospheric Turbulence. The effects of Atmospheric Turbulence intensity and information transmission rate on the BER performance of UV communication system are analyzed and simulated in this paper. It can be found that when the Atmospheric Turbulence intensity changes from weak to strong, the BER performance deteriorates along, and under the certain Atmospheric Turbulence intensity, information transmission rate will also have an impact on the system BER performance, the information transmission rate becomes faster, the BER performance gets worse.
Xiaomei Chen - One of the best experts on this subject based on the ideXlab platform.
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Analysis and modeling of Atmospheric Turbulence on the high-resolution space optical systems
8th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test Measurement Technology and Equipment, 2016Co-Authors: Jiang Lili, Xiaomei ChenAbstract:Modeling and simulation of optical remote sensing system plays an unslightable role in remote sensing mission predictions, imaging system design, image quality assessment. It has already become a hot research topic at home and abroad. Atmospheric Turbulence influence on optical systems is attached more and more importance to as technologies of remote sensing are developed. In order to study the influence of Atmospheric Turbulence on earth observation system, the Atmospheric structure parameter was calculated by using the weak Atmospheric Turbulence model; and the relationship of the Atmospheric coherence length and high resolution remote sensing optical system was established; then the influence of Atmospheric Turbulence on the coefficient r0h of optical remote sensing system of ground resolution was derived; finally different orbit height of high resolution optical system imaging quality affected by Atmospheric Turbulence was analyzed. Results show that the influence of Atmospheric Turbulence on the high resolution remote sensing optical system, the resolution of which has reached sub meter level meter or even the 0.5m, 0.35m and even 0.15m ultra in recent years, image quality will be quite serious. In the above situation, the influence of the Atmospheric Turbulence must be corrected. Simulation algorithms of PSF are presented based on the above results. Experiment and analytical results are posted.
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Image resolution analysis of Atmospheric Turbulence on the high-resolution space optical systems
2015 International Conference on Optical Instruments and Technology: Advanced Lasers and Applications, 2015Co-Authors: Lili Jiang, Xiaomei ChenAbstract:In order to study the influence of Atmospheric Turbulence on earth observation system, the Atmospheric structure parameter was calculated by using the weak Atmospheric Turbulence model; and the relationship of the Atmospheric coherence length and high resolution remote sensing optical system was established; then the influence of Atmospheric Turbulence on the coefficient r0h of optical remote sensing system of ground resolution was derived; finally different orbit height of high resolution optical system imaging quality affected by Atmospheric Turbulence was analyzed. Results show that the influence of Atmospheric Turbulence on the high resolution remote sensing optical system, the resolution of which has reached sub meter level meter or even the 0.5m, 0.35m and even 0.15m ultra in recent years, image quality will be quite serious. In the above situation, the influence of the Atmospheric Turbulence must be corrected.
Rod Frehlich - One of the best experts on this subject based on the ideXlab platform.
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Atmospheric Turbulence component of the innovation covariance
Quarterly Journal of the Royal Meteorological Society, 2008Co-Authors: Rod FrehlichAbstract:The innovation covariance is derived for general Atmospheric Turbulence conditions and for climatologies of upper-level Turbulence based on aircraft data. Error is defined in terms of the effective spatial filter of the forecast model to produce a consistent definition of measurement error and model error. Calculations of the Atmospheric Turbulence component (observation sampling-error covariance) are performed for rawinsonde data and various forecast model resolutions. Significant contributions from the Atmospheric Turbulence field are produced, especially for the older forecast models. Copyright © 2008 Royal Meteorological Society
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Measurements of the Atmospheric Turbulence spectrum and intermittency using laser scintillation
Propagation Engineering: Fourth in a Series, 1991Co-Authors: Rod FrehlichAbstract:Simultaneous measurements of the spatial intensity covariance of laser scintillation and the variance of integrated intensity collected by multiple circular apertures provide sufficient information to determine the form of the Atmospheric Turbulence spectrum over short spatial and temporal scales. This ensures local stationary of the Turbulence. The estimated parameters of the Turbulence spectrum (level of Turbulence C2n and inner scale) over these stationary events provide accurate estimates of the intermittency of Atmospheric Turbulence. The advantages of laser scintillation measurements include spatial averaging that improves statistical accuracy, true measurements of spatial statistics without the need to convert temporal statistics to spatial using Taylor's hypothesis, remote sensing of Atmospheric Turbulence which reduces contamination by support structures, and rugged instrumentation for reliable measurements. New uses of laser scintillation measurements will be discussed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Francis Laclare - One of the best experts on this subject based on the ideXlab platform.
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Atmospheric Turbulence and Solar Diameter Measurement
Lecture Notes in Physics, 2003Co-Authors: Abdanour Irbah, Julien Borgnino, Abd-errezak Bouzid, Lyes Lakhal, Nassim Seghouani, Christian Delmas, Francis LaclareAbstract:Object images obtained by mean of ground based instrument are degraded by the earth atmosphere. Indeed, the wave-front at the entrance of the instrument pupil, present phase and amplitude random fluctuations depending of the time, the position and the line of sight. The recorded images are consequently filtered leading to bad measurements of the studied object parameters. To qualify the Atmospheric degradations, several parameters are commonly defined. For solar diameter measurements performed with an astrolabe, errors due to the Atmospheric Turbulence are directly related to these parameters. After, a brief recall of the basic properties of the Atmospheric Turbulence, a method allowing to generate realistic random wave-fronts will be presented. They will be used to study errors on diameter measurements performed with a solar astrolabe. The obtained results will clearly show the necessity to have a seeing monitor observing together with the solar experiment. A method allowing to obtain the observation conditions for solar observation will then be given.
Jixiang Yan - One of the best experts on this subject based on the ideXlab platform.
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Simulation of Atmospheric Turbulence layers with phase screens by JAVA
Optical Design and Testing III, 2007Co-Authors: Xiaofang Zhang, Wenqin Chen, Jixiang YanAbstract:In multiconjugate Adaptive Optics (MCAO), the phase screens are used to simulate Atmospheric Turbulence layers to study the optimal Turbulence delamination and the determination of layer boundary position. In this paper, the method of power spectrum inversion and sub-harmonic compensation were used to simulate Atmospheric Turbulence layers and results can be shown by grey map. The simulation results showed that, with the increase of Turbulence layers, the RMS of adaptive system decreased, but the amplitude diminished. So the Atmospheric Turbulence can be split into 2-3 layers and be modeled by phase screens. Otherwise, a small simulation Atmospheric Turbulence delamination system was realized by JAVA.
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Influences of Atmospheric Turbulence on image resolution of optical remote sensing system
Adaptive Optics and Applications III, 2004Co-Authors: Xiaofang Zhang, Jixiang YanAbstract:The influences of Atmospheric Turbulence on image resolution of space-borne optical remote sensing system are discussed. The coherence length of wavefront r0 and the variance of angle-of-arrival fluctuation σ2α of sensing system are the main basis to evaluate the Atmospheric influence on image resolution. In this paper, different Atmospheric Turbulence models are chose to calculate r0 and σ2α in order to analyze the influence of Atmospheric Turbulence, and the results show that the influence of Atmospheric Turbulence should be weak and in most cases could be ignored for space-borne optical sensing system.
