Advances in airborne SAR interferometry using the experimental SAR system of DLR (original) (raw)
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Airborne differential sar interferometry: first results at l-band
IEEE Transactions on Geoscience and Remote Sensing, 2003
In recent years, differential interferometry using spaceborne synthetic aperture radar (SAR) sensors has become an established technique for detecting and monitoring centimeter-scale deformations of the earth's surface, as well as glacier flows and land slides. Although often very efficient, the use of spaceborne SAR data has several drawbacks, namely phase artifacts caused by atmospheric effects and very low coherence due to long data acquisition intervals and the short radar wavelength of the sensor. Most important, current spaceborne sensors are not able to ensure flexible monitoring of critical regions. Airborne sensors may overcome most of the problems mentioned above, but up to now, the operational use of airborne differential SAR interferometry has been prevented by insufficiently accurate motion compensation of the platform. In this letter, first results of airborne differential interferometry using the German Aerospace Center (DLR) experimental SAR system (E-SAR) in the interferometric repeat-pass mode are addressed. This includes an analysis of long-term decorrelation behavior in L-band and, particularly, the correction of residual motion errors in heavily decorrelated interferograms. A first differential interferogram of agricultural and forested areas is presented and analyzed.
Advanced Differential SAR Interferometric Techniques Applied to Airborne Data
This paper presents airborne DInSAR results using a stack of 14 images, acquired by the E-SAR system of DLR during a time span of only three hours and fifteen minutes. An advanced differential technique is used in order to retrieve the error in the digital elevation model (DEM) and the temporal evolution of the deformation for every coherent pixel in the image. Furthermore, some modifications in the differential processing chain are included in order to deal with the existence of the so-called residual motion errors, which play a similar role as the atmospheric artifacts in the spaceborne case. The detected deformation of a corner reflector and of some agricultural fields allows to validate the proposed techniques to measure deformation phenomena with an airborne platform.
On the requirements of SAR processing for airborne differential interferometry
Airborne Differential SAR Interferometry (D- InSAR) is still a challenging task when compared to the spaceborne case due to the fact that airborne platforms are unable to describe a stable flight track. For that reason a very precise motion compensation which includes the correction of topographic-induced phase errors has to be performed in the airborne SAR data. This paper presents the required steps of phase correction to achieve accurate airborne D-InSAR data. The latest airborne D-InSAR processing chain of the E-SAR system is shown. Differential interferograms results using the proposed processing chain are also shown. I. INTRODUCTION Differential Interferometry using Synthetic Aperture Radar, D-InSAR, is a technique to measure movements of the Earth's surface at sub-wavelength scale. The D-InSAR technique uses the interferometric phases to measure the changes in the path- length between two acquisition times. The interferometric phase between two SAR images taken at differ...
1999
This paper presents first the relevant parameters of the experimental E-SAR system for single-and repeat-pass SAR interferometry. The implementation of the different interferometric operation modes is described and special attention is paid to the problems posed by the unstable airborne platform. Each interferometric mode is described including the solution of its critical problems. The given examples prove the enormous information content one can obtain from the different imaging modes of airborne SAR interferometry. Finally, future developments concerning polarimetric SAR interferometry and tomography will be addressed.
IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium, 2008
We made a ground-based synthetic aperture radar (GB-SAR) system and tested its interferometric SAR (InSAR) measurement on the displacement of a trihedral corner reflector with atmospheric correction in terms of humidity and range. The GB-SAR worked at C-band with the synthetic aperture length of 5 m. Fully-polarimetric images were obtained with resolutions of 25 cm in range and 0.32 degree in azimuth direction. Located 160 m away from the system, the reflector was moved from 1mm to 40mm toward the system during each acquisition. An atmospheric correction function was obtained in terms of humidity and range by analyzing the phase of several stationary targets. The result showed an atmospheric delay of 3 mm at 160 m range when humidity changed from 47% to 58%. After atmospheric correction, DInSAR error was less than 1 mm with the correlation coefficient of 0.9999 when compared with the actual displacements. We concluded that atmospheric correction should be reinforced somehow for most spaceborne InSAR applications.
2008
Airborne SAR systems are traditionally considered to be a suitable testbed for the demonstration of new Earth observation data acquisition techniques and for the development of new applications based on the acquired multi parameter data sets. Spaceborne SAR system concepts and mission design is based on the experience gathered from these airborne SAR experiments and from dedicated campaigns. DLR's E-SAR system is supporting these activities since the late 1980-ties by providing high resolution multi-frequency and multi-polarisation data sets to a large user community. Triggered by the scientific needs and also by the recent advancements in motion compensation techniques several new operating modes are now available for the E-SAR system on a quasi-operational basis. This paper gives an overview of these techniques and presents novel application examples.