The increased complexity of multi-channel SAR sensors and the real-time on-board phase/amplitude correction requirement poses new challenges for the calibration, which cannot rely on current calibration techniques. On the other hand, the digital hardware utilized in multi-channel SAR systems, offer entirely new opportunities for the calibration such as on-board error correction and digital calibration. An internal calibration strategy for future digital beamforming SAR instruments is detailed and its performance analyzed using a dedicated calibration simulator software.

The increasing complexity of multi-channel SAR sensors and the real-time on-board phase/amplitude correction requirement pose new challenges for the calibration, which cannot rely on state-of-the-art calibration techniques. On the other hand, the digital hardware utilized in multi-channel SAR systems, offer new opportunities for the calibration such as on-board error correction and digital calibration. This paper addresses the internal calibration strategy for future digital beamforming SAR instruments and details the implementation of a dedicated calibration simulator software.

Future synthetic aperture radar (SAR) systems will incorporate multi-channel Digital Beam-Forming (DBF) capabilities and operate in new modes. These SAR instruments offer new opportunities but also challenges for calibration. For example on-board real time channel adjustment is unavoidable, but then the on-board digital signal processing capabilities are also readily available in DBF SAR. In any case, current instrument calibration concepts can not be extrapolated to future multi-channel SAR. Thus a new approach is requires required here. This paper reviews the calibration functionality of state-of-the-art spaceborne SAR and then suggest a calibration concept for future SAR.

Instrument calibration has ever been essential to synthetic aperture radar. This paper reviews the calibration functionality of current state-of-the-art spaceborne SAR and then proceeds to suggest calibration strategies for future SAR systems. These systems will incorporate multi-channel digital beamforming capabilities which offer new opportunities but also challenges for digital calibration. At the same time, the increased complexity of instrument calibration can not be extrapolated to future systems. This requires a reconsideration of the calibration strategy for spaceborne SAR. The paper is seen as a step in this direction.

The disturbance generated by ambiguous echoes is at the origin of a basic limitation of Synthetic Aperture Radar (SAR) spaceborne imaging: the trade-off between spatial resolution and swath extension. A tool to overcome this limitation is provided by ambiguity suppression techniques. Among these techniques, the Azimuth Phase Coding (APC) shows the appealing properties of having a low complexity and being effective against ambiguities originated by both point and distributed targets. Despite the number of investigations on the APC concept published in the last years, a proof of its capability based on real data is still missing in the literature. This paper focuses on the first APC test experiment based on real spaceborne SAR data. The experiment, realized by using the satellite TerraSAR-X, is described and its principal numerical results are presented.

The major objective of the ESA-funded TRP Activity was to design a spaceborne multi-channel Ka-band SAR optimized for detecting targets moving on land and ocean surfaces, and for estimating their position and motion parameters with high accuracy. A further objecitve was to investigate the capability of the system for ocean surface current measurements. At the conference the study results were presented.

This document is the output of Task 1 of the ESA Ka-band GMTI study. It provides a review of state-of-the-art single- and multi-channel techniques and algorithms for ground moving target indication and ocean current measurements, and a review of state-of-theart instruments. An analysis of these techniques and algorithms in terms target detection performance, computational load requirements, downlink data rates and need for training sequences is conducted. For each reviewed algorithm the advantages and drawbacks are identified. Potential scenarios of application are listed.

The proposed tests shall provide DRA mode data which will be analyzed by DLR to estimate the DRA mode performance. DLR will base its performance analysis on DRA mode performance test results as well as on functional test results. Topics to be covered are channel separation capability and DRA mode calibration accuracy. In addition the performance analysis of the test data shall help to optimize the DRA mode instrument operation w.r.t. RF performance.