Normal and Differential SAR Interferometry
GERMAN AEROSPACE CENTER (DLR) WESSLING (GERMANY) MICROWAVES AND RADAR INST
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SAR Interferometry explores the height structure inside a Radar pixel. Two antennas separated with a so called baseline distance B in cross velocity direction take two independent images from the same scene and compare the two phases which result from the same pixel at the two antennas. This phase differences compare to different distances between the pixel and the two antennas and from this difference the height of the respective pixel in relation to the altitude of the radar over a defined level can be determined. The Interferogramme formation will be explained and the respective terminology will be presented. In this context basic relations and important geometrical and electrodynamics system parameters will be presented and defined, the phase unwrapping will be considered as well as basic interferometry processing procedures and image formation principles. Coherence is the basis for Interferometry as well as a careful calibration. Therefore, the role of interferometric coherence for image interpretation will be shown. Errors caused by phase noise, de-correlation, co-registration misalignment, atmospheric disturbances, baseline limits, etc will be considered. They, principally, are the main reasons for coherence degradation. Different Interferometry modes Cross Track and Along Track Interferometry, single and dual pass Interferometry, Differential Interferometry, and Permanent Scattering Interferometry SAR will be discussed.
- Active and Passive Radar Detection and Equipment
- Radiofrequency Wave Propagation