SAR image extraction algorithm using nadir echo compensation for burst mode data of satellite altimeter

Abstract

As global warming progresses, the Earth is changing rapidly as polar glaciers become thinner and sea level rise. Therefore, in order to predict the progress of global warming, it is necessary to continuously monitor the Earth by mounting a radar to satellite. Radar is a device that detects objects by using radio waves. Among them, Synthetic Aperture Radar(SAR) is a radar specialized for observing the surface from the space. SAR concept is mainly applied to radar altimeters and imaging radars according to the indicator's characteristics to be measured. Radar altimeter is a radar for measuring the altitude of the surface and the imaging radar is to obtain two-dimensional images of the surface. Meanwhile, as satellite miniaturization technology is developed and high frequencies such as X, Ku, and K bands are preferred for precise measurement, the paradigm of the satellite industry is shifting from a large satellite to a micro satellite. However, since the radar altimeter and imaging radar have different principles and different hardware configurations, it is not easy to implement two functions with a single radar. Besides, since there is limitation on the load capacity that can be mounted on a micro satellite, it is also a burden to mount both altimeter and imaging radar on a single micro satellite. Therefore, the author applied a synthetic aperture concept to the burst mode altimeter data of CryoSat-2 satellite which is developed by the European Space Agency and devised a new 'Nadir Echo Compensation' technique to obtain surface images from altimeter data. The proposed methods are verified by point target simulation. The author expect this study to become a stepping stone for SAR imaging satellites to move to higher frequencies.