scholarly journals Synthetic aperture interferometric imaging using a passive microwave coding device

2016 ◽  
Author(s):  
Ettien Lazare Kpre ◽  
Cyril Decroze
Keyword(s):  
Passive Microwave ◽  
Synthetic Aperture ◽  
Interferometric Imaging

TERAHERTZ INTERFEROMETRIC AND SYNTHETIC APERTURE IMAGING

2007 ◽  
Vol 17 (02) ◽  
pp. 431-443 ◽  
Author(s):  
ALEXANDER M SINYUKOV ◽  
APARAJITA BANDYOPADHYAY ◽  
AMARTYA SENGUPTA ◽  
ROBERT B BARAT ◽  
DALE E GARY ◽  
...  
Keyword(s):  
Synthetic Aperture ◽  
Imaging Method ◽  
Interferometric Imaging ◽  
Metal Object ◽  
Security Applications ◽  
Concealed Weapons ◽  
Continuous Waves ◽  
Theoretical Predictions ◽  
Terahertz Frequencies ◽  
Good Agreement

Experimental results of homodyne terahertz interferometric 1-D and 2-D imaging are presented. The reconstructed images of a point source are in a good agreement with theoretical predictions. The performance of an N element detector array is imitated by only one detector placed at N positions. Continuous waves at 0.25-0.3 THz are used to detect a metal object behind a barrier. 1-D images of a C-4 sample have been obtained at several terahertz frequencies. Focusing issues of 2-D imaging have been demonstrated. The terahertz interferometric imaging method can be used in defense and security applications to detect concealed weapons, explosives as well as chemical and biological agents.

scholarly journals Snow Water Equivalent Change Mapping from Slope Correlated InSAR Phase Variations

2021 ◽  
Author(s):  
Jayson Eppler ◽  
Bernhard T. Rabus ◽  
Peter Morse
Keyword(s):  
Synthetic Aperture Radar ◽  
Snow Water Equivalent ◽  
Phase Unwrapping ◽  
Passive Microwave ◽  
Synthetic Aperture ◽  
Estimation Methods ◽  
Glacier Mass Balance ◽  
Drainage Basins ◽  
Snow Water ◽  
Aperture Radar

Abstract. Area-based measurements of snow water equivalent (SWE) are important for understanding earth system processes such as glacier mass balance, winter hydrological storage in drainage basins and ground thermal regimes. Remote sensing techniques are ideally suited for wide-scale area-based mapping with the most commonly used technique to measure SWE being passive-microwave, which is limited to coarse spatial resolutions of 25 km or greater, and to areas without significant topographic variation. Passive-microwave also has a negative bias for large SWE. Repeat-pass synthetic aperture radar interferometry (InSAR) as an alternate technique allows measurement of SWE change at much higher spatial resolution. However, it has not been widely adopted because: (1) the phase unwrapping problem has not been robustly addressed, especially for interferograms with poor coherence and; (2) SWE change maps scaled directly from repeat-pass interferograms are not an absolute measurement but contain unknown offsets for each contiguous coherent area. We develop and test a novel method for repeat-pass InSAR based dry-snow SWE estimation that exploits the sensitivity of the dry-snow refraction-induced InSAR phase to topographic variations. The method robustly estimates absolute SWE change at spatial resolutions of < 1 km, without the need for phase unwrapping. We derive a quantitative signal model for this new SWE change estimator and identify the relevant sources of bias. The method is demonstrated using both simulated SWE distributions and a 9-year RADARSAT-2 spotlight-mode dataset near Inuvik, NWT, Canada. SWE results are compared to in situ snow survey measurements and estimates from ERA5 reanalysis. Our method performs well in high-relief areas and in areas with high SWE (> 150 mm), thus providing complementary coverage to other passive- and active-microwave based SWE estimation methods. Further, our method has the advantage of requiring only a single wavelength band and thus can utilize existing spaceborne synthetic aperture radar systems. In application, a first order analysis of SWE trends within three drainage basins suggests that differences between basin-level accumulations are a function of major landcover types, and that re-vegetation following a forest-tundra fire that occurred over 50 years ago continues to affect the spatial distribution of SWE accumulation in the study area.

Terahertz Synthetic Aperture and Interferometric Imaging

2007 ◽  
Author(s):  
John F. Federici ◽  
Alexander M. Sinyukov ◽  
Robert B. Barat ◽  
Dale E. Gary ◽  
Zoi-Heleni Michalopoulou
Keyword(s):  
Synthetic Aperture ◽  
Interferometric Imaging
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