The SAR Signal Processing department produces image products to support earth observation activities. Important application areas include the measurement and analysis of earthquakes and movement associated with volcanoes and glaciers.
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 a complex 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 and in some cases for Copernicus missions. At present these are the TerraSAR-X, the TanDEM-X and the Sentinel-1 missions. An important milestone was also the Shuttle Radar Topography Mission (SRTM).
The most important products resulting from these missions are calibrated SAR images, digital terrain models, and ground movement maps for science and commercial users.
The department’s research specializes on measuring small movements of the earth surface with the help of SAR interferometry. The focus of interest is metropolitan areas, volcanoes, earthquake regions and glaciers.
In addition to relative interferometric measurements, the department has developed a new methodology for absolute geodetic SAR measurements. Imaging geodesy yields absolute measurements comparable with those from GNSS.
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.