Time reversal SAR technique for imaging extended target shielded from line-of-sight

2008 ◽  
Author(s):  
Yi Jiang ◽  
Jian-Gang Zhu
Keyword(s):  
Time Reversal ◽  
Line Of Sight ◽  
Extended Target

scholarly journals On the Performance of the Time Reversal SM-MIMO-UWB System on Correlated Channels

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hieu Nguyen ◽  
Van Duc Nguyen ◽  
Trung Kien Nguyen ◽  
Kiattisak Maichalernnukul ◽  
Feng Zheng ◽  
...  
Keyword(s):  
Spatial Correlation ◽  
Time Reversal ◽  
Channel Model ◽  
Line Of Sight ◽  
Channel Measurements ◽  
Virtual Mimo ◽  
Correlated Channels ◽  
Multiple Transmit ◽  
Correlated Channel ◽  
The Impact

The impact of spatial correlation on the multi-input multi-output ultrawide band (MIMO-UWB) system using the time reversal (TR) technique is investigated. Thanks to TR, several data streams can be transmitted by using only one antenna in a system named virtual MIMO-TRUWB. Since the virtual MIMO-TR-UWB system is not affected by the transmit correlation, under the condition of the high spatial correlation, it outperforms the true MIMO-UWB system with multiple transmit antennas. The channel measurements are performed in short-range indoor environment, both line-of-sight and non-line-of-sight to verify the adopted correlated channel model.

Time-Reversal Imaging of Extended Source Terms

2015 ◽  
Author(s):  
Habib Ammari ◽  
Elie Bretin ◽  
Josselin Garnier ◽  
Hyeonbae Kang ◽  
Hyundae Lee ◽  
...  
Keyword(s):  
Wave Equation ◽  
Time Reversal ◽  
Imaging Techniques ◽  
Main Idea ◽  
Field Measurements ◽  
Characteristic Size ◽  
Source Terms ◽  
Extended Source ◽  
Use Of Time ◽  
Extended Target

This chapter describes the use of time-reversal imaging techniques for extended source terms from far-field measurements. A target or a source term is called extended when its characteristic size times the operating frequency (wavenumber) is considerably larger than one. For the scalar wave equation, the main idea of time reversal is to take advantage of its reversibility in order to backpropagate signals to the sources that emitted them. The chapter focuses on the homogeneous isotropic elastic wave equation in a d-dimensional open medium with d = 2, 3. It first reconstructs shape changes of an extended target before introducing a number of algorithms and analyzing their resolution and stability for the linearized reconstruction problem. Finally, it discusses optimal control approaches for solving the nonlinear problem.

Variation of the amount of hydrogen along the galactic ridge

1967 ◽  
Vol 31 ◽  
pp. 171-172
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Surface Brightness ◽  
Milky Way ◽  
Neutral Hydrogen ◽  
Line Of Sight ◽  
Optical Surface ◽  
Hydrogen Density ◽  
Continuous Radiation ◽  
Galactic Longitude

The integralNHof neutral-hydrogen density along the line of sight is determined from the Kootwijk and Sydney surveys. The run ofNHwith galactic longitude agrees well with that of thermal continuous radiation and that of the optical surface brightness of the Milky Way.

Structuring, Motions and Shapes of Corona Emission Line Profiles

1994 ◽  
Vol 144 ◽  
pp. 421-426
Author(s):  
N. F. Tyagun
Keyword(s):  
Emission Line ◽  
Filling Factor ◽  
Direct Relationship ◽  
Coronal Plasma ◽  
Line Of Sight ◽  
Line Profiles ◽  
The Difference ◽  
Yellow Line ◽  
Red Line

AbstractThe interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.

HUMAN LIMITATIONS OF LINE OF SIGHT MISSILES DURING LIMITED VISIBILITY.

1968 ◽  
Author(s):  
ANDREW J. ECKLES ◽  
THOMAS A. GARRY ◽  
WILLIAM C. MULLEN
Keyword(s):  
Line Of Sight ◽  
Limited Visibility

Alignment Tolerance in Multiple-Stream Transmission Using Orthogonal Directivities under Line-of-Sight Environments

2016 ◽  
Vol E99.B (6) ◽  
pp. 1362-1370 ◽  
Author(s):  
Maki ARAI ◽  
Tomohiro SEKI ◽  
Ken HIRAGA ◽  
Kazumitsu SAKAMOTO ◽  
Tadao NAKAGAWA
Keyword(s):  
Line Of Sight
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