Calibration of DLR's Experimental Airborne SAR System E-SAR.

Abstract

Operational calibration of E-SAR requires both external calibration and internal monitoring of the sensor including a recording of instabilities of the transmit power or the receiver gain. Extensive measurements of the receiver gain curve for different settings of the automatic gain control (AGC) have been performed in the laboratory. The output power is being controlled even during data takes using power sensors at the antenna input. For the purpose of external calibration we deploy trihedral corner reflectors in the area surrounding DLR and image these targets at the beginning and the end of each campaign. The analysis of the corresponding image data allows to derive the absolute calibration factor and gives an estimate of the remaining error in radiometric corrections.