scholarly journals Point-ahead analysis and pre-pointing link stability study of intersatellite laser communication

2020 ◽  
Vol 50 (1) ◽  
Author(s):  
Fu-rui Zhang ◽  
Jun-feng Han ◽  
Ping Ruan
Keyword(s):  
Analytical Investigation ◽  
Stability Study ◽  
Laser Communication ◽  
Bias Error ◽  
Long Distance ◽  
Error Angle ◽  
The Monte Carlo Method ◽  
Link Stability ◽  
Link Budget ◽  
Communication System Design

The static bias error angle obviously affects pre-pointing links’ stability in the presence of vibration in intersatellite laser communication. The 2nd order point-ahead angle is a source of misalignment which was ignored in most solutions, and this is the concern of our paper. In this study, we present a further analytical investigation into the point-ahead angle in complex satellite maneuvering environment. Static bias error angle induced by the 2nd order point-ahead angle has been studied under different intersatellite links. The probability density function of the pre-pointing links’ outage has been derived in the presence of pointing jitter taking consideration of the static bias angle, and the link budget has also been analyzed. Simulation model of link stability has been established to verify the numerical results by the Monte Carlo method in Matlab-Simulink environment. The results have shown that the 2nd order point-ahead angle has a significant detrimental impact on link stability in long distance links. It is a neglectable factor. This work is dedicated to intersatellite laser communication system design.

Visible Light Communication System Design and Link Budget Analysis

2015 ◽  
Vol 33 (24) ◽  
pp. 5201-5209 ◽  
Author(s):  
Babar Hussain ◽  
Xianbo Li ◽  
Fengyu Che ◽  
C. Patrick Yue ◽  
Liang Wu
Keyword(s):  
Visible Light ◽  
System Design ◽  
Communication System ◽  
Visible Light Communication ◽  
Budget Analysis ◽  
Link Budget ◽  
Communication System Design

Laser Communication System Design

1988 ◽  
Author(s):  
W. L. Casey ◽  
G. R. Doughty ◽  
J. G. Houston, ◽  
R. K. Marston ◽  
L. J. O'Pella ◽  
...  
Keyword(s):  
System Design ◽  
Communication System ◽  
Laser Communication ◽  
Communication System Design

Unbiased Nonlinear Least Squares Estimations of Short-distance Equations

2017 ◽  
Vol 70 (4) ◽  
pp. 810-828 ◽  
Author(s):  
Shuqiang Xue ◽  
Yuanxi Yang
Keyword(s):  
Least Squares ◽  
Short Distance ◽  
Iterative Procedure ◽  
Nonlinear Least Squares ◽  
Long Distance ◽  
Geometrical Condition ◽  
Least Squares Solution ◽  
The Monte Carlo Method ◽  
Linearization Error ◽  
Geometric Dilution Of Precision

Nonlinear least squares estimations have been widely applied in positioning. However, nonlinear least squares estimations are generally biased. As the Gauss-Newton method has been widely applied to obtain a nonlinear least squares solution, we propose an iterative procedure for obtaining unbiased estimations with this method. The characteristics of the linearization error are discussed and a systematic error source of the linearization error needs to be removed to guarantee the unbiasedness. Both the geometrical condition and the statistical condition for unbiased nonlinear least squares estimations are revealed. It is shown that for long-distance observations of high precision, or for a positioning configuration with the lowest Geometric Dilution Of Precision (GDOP), the nonlinear least squares estimations tend to be unbiased; but for short-distance cases, the bias in the nonlinear least squares solution should be estimated to obtain unbiased values by removing the bias from the nonlinear least squares solution. The proposed results are verified by the Monte Carlo method and this shows that the bias in nonlinear least squares solution of short-distance distances cannot be ignored.

scholarly journals Compressive Sensing Imaging Based on Modulation of Atmospheric Scattering Medium

2020 ◽  
Vol 10 (13) ◽  
pp. 4466
Author(s):  
Xuelin Lei ◽  
Xiaoshan Ma ◽  
Zhen Yang ◽  
Xiaodong Peng ◽  
Yun Li ◽  
...  
Keyword(s):  
Compressive Sensing ◽  
Digital Micromirror Device ◽  
Scattering Media ◽  
Long Distance ◽  
Ongoing Research ◽  
Compressive Imaging ◽  
Atmospheric Scattering ◽  
The Monte Carlo Method ◽  
Imaging Approach ◽  
Single Pixel

Long-distance imaging in time-varying scattering media, such as atmosphere, is a significant challenge. Light is often heavily diffused while propagating through scattering media, because of which the clear imaging of objects concealed by media becomes difficult. In this study, instead of suppressing diffusion by multiple scattering, we used natural randomness of wave propagation through atmospheric scattering media as an optimal and instantaneous compressive imaging mechanism. A mathematical model of compressive imaging based on the modulation of atmospheric scattering media was established. By using the Monte Carlo method, the atmospheric modulation matrix was obtained, and the numerical simulation of modulation imaging of atmospheric scattering media was performed. Comparative experiments show that the atmospheric matrix can achieve the same modulation effect as the Hadamard and Gaussian random matrices. The effectiveness of the proposed optical imaging approach was demonstrated experimentally by loading the atmospheric measurement matrix onto a digital micromirror device to perform single pixel compressive sensing measurements. Our work provides a new direction to ongoing research in the field of imaging through scattering media.

A chain is as strong as its weakest link – Stability study of MAPbI3 under light and temperature

2019 ◽  
Vol 29 ◽  
pp. 10-19 ◽  
Author(s):  
Philippe Holzhey ◽  
Pankaj Yadav ◽  
Silver-Hamill Turren-Cruz ◽  
Amita Ummadisingu ◽  
Michael Grätzel ◽  
...  
Keyword(s):  
Stability Study ◽  
Weakest Link ◽  
Link Stability ◽  
A Chain

Reliability Calculation Method for Natural Gas Pipelines with Girth Weld Defects Identified through In-Line Inspection

2019 ◽  
Vol 795 ◽  
pp. 225-232 ◽  
Author(s):  
Ming Fei Li ◽  
Jian Chen ◽  
Zheng Qiang Lei ◽  
Hong Long Zheng ◽  
Zai Rong Li
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Plastic Material ◽  
Pipeline System ◽  
Long Distance ◽  
Weld Defects ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
The Monte Carlo Method ◽  
Reliability Assessments

To introduce a method for reliability analysis of China's large-scale natural gas pipeline system, one should first have a method to calculate the reliability of pipe segments, compressors, valves, and other factors. This article models the rules prescribed in BS7910-2013, a guide to methods for assessing the acceptability of flaws in metallic structures, and combines pipeline reliability assessments from CSA Z662-2015 to present a method (based on the Monte Carlo method) to calculate the failure probability/reliability of long-distance pipelines containing a large number of girth weld defects. The method involves the destruction of plastic material, brittle fracture failure analysis, consideration of the division of units by using pipeline area classes for calculation, and reliability index analysis. The results of a magnetic flux leakage (MFL) in-line inspection (ILI) of a defective girth weld from a section of a pipeline in China are used to demonstrate how to determine the reliability of the entire pipeline.

Laser communication system design for the Google Lunar X-Prize

2011 ◽  
Author(s):  
Sreeja Nag ◽  
Edwin Gomez ◽  
Sam Feller ◽  
Jonathan Gibbs ◽  
Jeffrey Hoffman
Keyword(s):  
System Design ◽  
Communication System ◽  
Laser Communication ◽  
Communication System Design
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