scholarly journals Deceptive Targets Generation Simulation Against Multichannel SAR

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 597
Author(s):  
Penghui Ji ◽  
Shiqi Xing ◽  
Dahai Dai ◽  
Bo Pang
Keyword(s):  
Synthetic Aperture ◽  
Minimum Condition ◽  
Complex Coefficient ◽  
Sar Images ◽  
Digital Elevation ◽  
Deceptive Jamming ◽  
Elevation Model ◽  
Interferometric Sar ◽  
General Architecture ◽  
Ground Moving Target Indication

Traditional synthetic aperture radar (SAR) deceptive jamming can effectively generate deceptive scenes or false targets in SAR images. However, these false targets or scenes can be easily distinguished or eliminated by the multichannel SAR system. To interfere with the multichannel SAR, we first analyzed the results of SAR deceptive jamming generated by one transponder and two transponders against three-channel SAR- ground moving target indication (GMTI). Then, we propose a new deceptive jamming method against three-channel SAR-GMTI by using three synergetic transponders. By modulating each transponder with a complex coefficient, three synergetic transponders can generate false moving targets with the controllable radial velocity and located azimuth position in three-channel SAR-GMTI. Besides, in this paper, we also introduce an algorithm to deploy three transponders reasonably by utilizing the minimum condition number. In the end, a general architecture of multiple transponders deceiving multichannel SAR is given. The proposed method can not only generate deceptive false targets against multichannel SAR-GMTI, but also guide the production of a deceptive digital elevation model (DEM) against multichannel interferometric SAR (InSAR). Simulations verify the effectiveness of the proposed method.

scholarly journals Evaluation of Atmospheric Effects on Interferograms Using DEM Errors of Fixed Ground Points

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2336 ◽  
Author(s):  
Takashi Nonaka ◽  
Tomohito Asaka ◽  
Keishi Iwashita
Keyword(s):  
Phase Noise ◽  
Atmospheric Effects ◽  
Sar Images ◽  
Single Pass ◽  
Digital Elevation ◽  
Total Phase ◽  
Disaster Monitoring ◽  
The Difference ◽  
Elevation Model ◽  
Interferometric Sar

High-resolution synthetic aperture radar (SAR) data are widely used for disaster monitoring. To extract damaged areas automatically, it is essential to understand the relationships among the sensor specifications, acquisition conditions, and land cover. Our previous studies developed a method for estimating the phase noise of interferograms using several pairs of TerraSAR-X series (TerraSAR-X and TanDEM-X) datasets. Atmospheric disturbance data are also necessary to interpret the interferograms; therefore, the purpose of this study is to estimate the atmospheric effects by focusing on the difference in digital elevation model (DEM) errors between repeat-pass (two interferometric SAR images acquired at different times) and single-pass (two interferometric SAR images acquired simultaneously) interferometry. Single-pass DEM errors are reduced due to the lack of temporal decorrelation and atmospheric disturbances. At a study site in the city of Tsukuba, a quantitative analysis of DEM errors at fixed ground objects shows that the atmospheric effects are estimated to contribute 75% to 80% of the total phase noise in interferograms.

scholarly journals SAR Interferometric Baseline Refinement Based on Flat-Earth Phase without a Ground Control Point

2020 ◽  
Vol 12 (2) ◽  
pp. 233 ◽  
Author(s):  
Bing Xu ◽  
Zhiwei Li ◽  
Yan Zhu ◽  
Jiancun Shi ◽  
Guangcai Feng
Keyword(s):  
Control Point ◽  
Least Square ◽  
Synthetic Aperture ◽  
Ground Control ◽  
Ground Control Point ◽  
Refinement Method ◽  
Digital Elevation ◽  
Elevation Model ◽  
Interferometric Sar ◽  
Baseline Estimation

Interferometric baseline estimation is a key procedure of interferometric synthetic aperture radar (SAR) data processing. The error of the interferometric baseline affects not only the removal of the flat-earth phase, but also the transformation coefficient between the topographic phase and elevation, which will affect the topographic phase removal for differential interferometric SAR (D-InSAR) and the accuracy of the final generated digital elevation model (DEM) product for interferometric synthetic aperture (InSAR). To obtain a highly accurate interferometric baseline, this paper firstly investigates the geometry of InSAR imaging and establishes a rigorous relationship between the interferometric baseline and the flat-earth phase. Then, a baseline refinement method without a ground control point (GCP) is proposed, where a relevant theoretical model and resolving method are developed. Synthetic and real SAR datasets are used in the experiments, and a comparison with the conventional least-square (LS) baseline refinement method is made. The results demonstrate that the proposed method exhibits an obvious improvement over the conventional LS method, with percentages of up to 51.5% in the cross-track direction. Therefore, the proposed method is effective and advantageous.

scholarly journals GEOREFERENCING ON SYNTHETIC APERTURE RADAR IMAGERY

2015 ◽  
Vol XL-1-W5 ◽  
pp. 179-184
Author(s):  
M. Esmaeilzade ◽  
J. Amini ◽  
S. Zakeri
Keyword(s):  
Synthetic Aperture Radar ◽  
Digital Elevation Model ◽  
Synthetic Aperture ◽  
Geometric Distortion ◽  
Original Image ◽  
Sar Images ◽  
Geometric Distortions ◽  
Digital Elevation ◽  
Elevation Model ◽  
Aperture Radar

Due to the SAR<sup>1</sup> geometry imaging, SAR images include geometric distortions that would be erroneous image information and the images should be geometrically calibrated. As the radar systems are side looking, geometric distortion such as shadow, foreshortening and layover are occurred. To compensate these geometric distortions, information about sensor position, imaging geometry and target altitude from ellipsoid should be available. In this paper, a method for geometric calibration of SAR images is proposed. The method uses Range-Doppler equations. In this method, for the image georeferencing, the DEM<sup>2</sup> of SRTM with 30m pixel size is used and also exact ephemeris data of the sensor is required. In the algorithm proposed in this paper, first digital elevation model transmit to range and azimuth direction. By applying this process, errors caused by topography such as foreshortening and layover are removed in the transferred DEM. Then, the position of the corners on original image is found base on the transferred DEM. Next, original image registered to transfer DEM by 8 parameters projective transformation. The output is the georeferenced image that its geometric distortions are removed. The advantage of the method described in this article is that it does not require any control point as well as the need to attitude and rotational parameters of the sensor. Since the ground range resolution of used images are about 30m, the geocoded images using the method described in this paper have an accuracy about 20m (subpixel) in planimetry and about 30m in altimetry. <br><br> <sup>1</sup> Synthetic Aperture Radar <br> <sup>2</sup> Digital Elevation Model

scholarly journals An Improved R-Index Model for Terrain Visibility Analysis for Landslide Monitoring with InSAR

2021 ◽  
Vol 13 (10) ◽  
pp. 1938
Author(s):  
Tianhe Ren ◽  
Wenping Gong ◽  
Victor Mwango Bowa ◽  
Huiming Tang ◽  
Jun Chen ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Poor Performance ◽  
Synthetic Aperture ◽  
Landslide Monitoring ◽  
Sar Images ◽  
Index Model ◽  
Digital Elevation ◽  
Terrain Effect ◽  
Elevation Model ◽  
Aperture Radar

The interferometric synthetic aperture radar (InSAR) technique is widely adopted for detecting and monitoring landslides, but its effectiveness is often degraded in mountainous terrains, due to geometric distortions in the synthetic aperture radar (SAR) image input. To evaluate the terrain effect on the applicability of InSAR in landslide monitoring, a variety of visibility evaluation models have been developed, among which the R-index models are quite popular. In consideration of the poor performance of the existing R-index models in the passive layover region, this study presents an improved R-index model, in which a coefficient for improving the visibility evaluation in the far passive layover regions is incorporated. To demonstrate the applicability of the improved R-index model, the terrain visibility of SAR images in Fengjie, a county in the Three Gorges Reservoirs region, China, is studied. The effectiveness of the improved R-index model is demonstrated through comparing the visibility evaluation results with those obtained from the existing R-index models and P-NG method. Further, the effects of the line-of-sight (LOS) parameters of SAR images and the resolution of the digital elevation model (DEM) on the terrain visibility are discussed.

scholarly journals Topography and dynamics of Austfonna, Nordaustlandet, Svalbard, from SAR interferometry

1997 ◽  
Vol 24 ◽  
pp. 403-408 ◽  
Author(s):  
Beverley Unwin ◽  
Duncan Wingham
Keyword(s):  
Sar Interferometry ◽  
Synthetic Aperture ◽  
Drainage Basins ◽  
Ice Caps ◽  
Radar Images ◽  
Differential Interferometry ◽  
Digital Elevation ◽  
Radio Echo Sounding ◽  
Velocity Information ◽  
Elevation Model

The ice caps of Nordaustlandet, Svalbard, represent one of the largest glaciated areas outside of Antarctica and Greenland. They demonstrate a variety of different flow regimes within a comparatively compact area. We report on the first interferometrically derived elevation models and velocity visualisations of Austfonna. This initial investigation had three purposes: to determine whether the coherence and velocity characteristics of the region permitted interferometric survey; to determine the accuracy of derived elevations; and to assess the possibility of investigating time-variant flow of the more dynamic ice bodies using differential interferometry. A trio of coherent synthetic aperture radar images from ERS-1 ’s First Ice Phase was identified. The images were combined to separate the topographic and velocity components of the resultant interferograms. The topographic phase difference was used to produce a digital elevation model of Austfonna. Its accuracy relative to radio-echo-sounding derived tie-points is 8 m and its resolution 40 m. We also present synoptic views of the velocity field of three of Austfonna’s drainage basins, and comment on the extraction of useful velocity information.

Multichannel interferometric SAR phase unwrapping using extended Kalman Smoother

2013 ◽  
Vol 5 (3) ◽  
pp. 429-436 ◽  
Author(s):  
Davide Chirico ◽  
Gilda Schirinzi
Keyword(s):  
Phase Unwrapping ◽  
Sensor Data ◽  
Bayesian Estimator ◽  
Bayesian Approaches ◽  
Strong Discontinuities ◽  
Absolute Phase ◽  
Multi Sensor Data Fusion ◽  
Digital Elevation ◽  
Elevation Model ◽  
Interferometric Sar

Phase unwrapping (PU) is one of the key processing steps in reconstructing the digital elevation model (DEM) of a scene from interferometric synthetic aperture radar (InSAR) data. The PU problem entails the estimation of an absolute phase from observation of its noisy principal (wrapped) values. Recently, PU approaches based on Kalman filtering have proved their efficacy in tackling the PU problem even when strong discontinuities of the height profile and noisy data are involved. This paper presents a novel multichannel InSAR PU algorithm using several interferometric SAR images based on the extended Kalman filter. The proposed technique exploits the capability of the Kalman algorithm to simultaneously perform noise filtering, PU, and multi-sensor data fusion. The proposed method, even being a Bayesian estimator, optimally fuses height information coming from an additional maximum likelihood estimator (MLE) combining the benefits of both the Bayesian and the non-Bayesian approaches. The performance of the proposed algorithm has been tested on simulated interferometric images proving the effectiveness of the proposed method.

scholarly journals ICESAT VALIDATION OF TANDEM-X I-DEMS OVER THE UK

2016 ◽  
Vol XLI-B4 ◽  
pp. 129-136 ◽  
Author(s):  
L. Feng ◽  
J.-P. Muller
Keyword(s):  
Slope Aspect ◽  
Surface Slope ◽  
Grid Spacing ◽  
Digital Elevation ◽  
X Band ◽  
Elevation Data ◽  
Vertical Accuracy ◽  
Elevation Model ◽  
The Uk ◽  
Interferometric Sar

From the latest TanDEM-X mission (bistatic X-Band interferometric SAR), globally consistent Digital Elevation Model (DEM) will be available from 2017, but their accuracy has not yet been fully characterised. This paper presents the methods and implementation of statistical procedures for the validation of the vertical accuracy of TanDEM-X iDEMs at grid-spacing of approximately 12.5&thinsp;m, 30&thinsp;m and 90&thinsp;m based on processed ICESat data over the UK in order to assess their potential extrapolation across the globe. The accuracy of the TanDEM-X iDEM in UK was obtained as follows: against ICESat GLA14 elevation data, TanDEM-X iDEM has &minus;0.028±3.654&thinsp;m over England and Wales and 0.316&thinsp;±&thinsp;5.286&thinsp;m over Scotland for 12&thinsp;m, &minus;0.073&thinsp;±&thinsp;6.575&thinsp;m for 30&thinsp;m, and 0.0225&thinsp;±&thinsp;9.251&thinsp;m at 90&thinsp;m. Moreover, 90&thinsp;% of all results at the three resolutions of TanDEM-X iDEM data (with a linear error at 90&thinsp;% confidence level) are below 16.2&thinsp;m. These validation results also indicate that derivative topographic parameters (slope, aspect and relief) have a strong effect on the vertical accuracy of the TanDEM-X iDEMs. In high-relief and large slope terrain, large errors and data voids are frequent, and their location is strongly influenced by topography, whilst in the low- to medium-relief and low slope sites, errors are smaller. ICESat derived elevations are heavily influenced by surface slope within the 70&thinsp;m footprint as well as there being slope dependent errors in the TanDEM-X iDEMs.

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