TerraSAR X Internal Calibration Experience and Extension for TanDEM X

Abstract

TerraSAR X is a high resolution synthetic aperture radar (SAR) satellite that was launched in 2007. Its twin satellite TanDEM X will join the mission on the second half of 2009, flying in a close helix formation, which will extend the acquisition capabilities of the system. Both satellites have identical active phased array X-Band antennas, each with 384 transmit/receive modules (TRMs) controlling the beam steering in azimuth and elevation. A calibration network provides monitoring of internal instrument behaviour by introducing additional calibration pulses. The proper evaluation of these calibration pulses for every acquisition guarantees high radiometric stability of all SAR products. The experience of TerraSAR X will be directly applied to the monostatic internal calibration of TanDEM X. However, bistatic acquisitions set a new challenge for the instrument calibration, and require an extension of the current techniques. This paper will summarize the most important results of the TerraSAR X instrument calibration and will propose some extensions for the bistatic operation mode.