Abstract :
Quasi-simultaneous radar images can be produced by a low cost system using a set of passive receivers onboard a constellation of microsatellites in a special orbital configuration. The combination of these images can improve the final resolution in range and azimuth and systematically produce across-track and along-track interferometric data. The author reviews some of the technical particularities of these systems linked to (1) the system, such as the pulse scheduling, the orbital geometry, and the required pointing and positioning, and (2) the image quality, such as the ambiguity level, the required clock stability, the effect of varying baselines at various scales, focusing to higher resolution, and geometric limitations, mainly the behavior of the coherent combinations over terrain with high slopes. The author illustrates three applications of the concept in cooperation with the radar onboard the Japanese ALOS satellite, the ASAR instrument onboard the European ENVISAT, and as a study-case for defense applications of the concept. The author envisions even more innovative applications of the concept, for instance in simultaneous polarimetry and interferometry
Keywords :
radar imaging; radiowave interferometry; remote sensing by radar; spaceborne radar; terrain mapping; ASAR instrument; European ENVISAT; Japanese ALOS satellite; ambiguity level; clock stability; defense applications; image quality; interferometric cartwheel; interferometric data; interferometry; low cost system; microsatellites; orbital configuration; orbital geometry; passive receivers; pointing; polarimetry; positioning; pulse scheduling; quasi-simultaneous radar images; terrain; varying baselines; Azimuth; Clocks; Costs; Geometry; Image quality; Image resolution; Passive radar; Radar imaging; Spaceborne radar; Stability;
