Synthetic Aperture Radar (SAR)
A SAR instrument scans the earth’s surface from aircraft or satellites with the help of microwave pulses. High resolution images and data products are generated from the reflected echoes. SAR methodology has two important advantages: it functions also at night and despite cloud cover, and it can be used to obtain reliable geophysical measurements such as backscatter constants or distances. This cannot be achieved with other imaging approaches and so SAR is preferentially employed during disaster situations, and also for continuous monitoring of polar areas, earthquake risk zones and volcanoes.
From raw data to geoscientific information
The raw data provided by the radar instrument first have to be processed before practical use, which requires an elaborate series of steps. The department has developed algorithms and software processors for the purpose. The range of areas addressed extends from raw data focusing to multidimensional interferometric analysis.
Processors for space missions
The SAR processors developed by the department are used in all civilian German SAR missions; at present these are the TerraSAR-X and TanDEM-X missions. An important milestone was also the Shuttle Radar Topography Mission (SRTM).The most important products resulting from these missions are calibrated SAR images and digital terrain models for science and commercial users.
The department’s research specializes on measuring small movements of the earth surface. The focus of interest is metropolitan areas, volcanoes, earthquake regions and glaciers. Another research topic is interferometric SAR tomography. With this methodology building surfaces can be measured three dimensionally. Even the movement of individual parts of a building can be recorded. This work is being undertaken in close cooperation with the Remote Sensing Technology Chair at Munich Technical University (TUM).And finally, the department is investigating Moving Target Indication (MTI) and Along-Track Interferometry (ATI). These technologies make it possible to measure vehicle speed and surface water flow from space.