Bistatic SAR systems have a high potential for scientific, commercial and security applications. One of the benefits is the possibility to generate highly accurate digital elevation models using bistatic interferometry. Examples for proposed bi- and multi-static satellite missions with interferometric capabilities are TanDEM-X and Cartwheel. Both are based on radar instruments placed on different spacecrafts, which gives rise to several technical challenges for the system realization. A factor which may severely degrade the performance of a bistatic SAR is the phase instability of the two oscillators involved. Investigations have shown, that, unless highly stable oscillators are used, the oscillators phase noise has to be compensated; this is possible through the processed SAR data in combination with ground control points, or by establishing a synchronization link to directly exchange signals providing information on the oscillator phase noise. The later method is based on recording the received demodulated phases, which are then used to derive a compensation signal to correct the SAR data. The paper describes a possible configuration for the synchronization link, sharing hardware components with the SAR instrument. Such a system is currently intended for the TanDEM-X mission. The resulting restrictions on the synchronization scheme, timing, and accuracy are investigated. The statistical properties of the compensation signal are used to derive a figure-of-merit for synchronization performance. The focus is on the influence of the synchronization link RF hardware on the quality of the derived compensation signal. Therefore a hardware setup is realized and characterized to obtain realistic data. Further, a simulation tool is implemented to predict the performance. The simulation tool is based on a synchronization link hardware model which can use measurement data as an input. Finally, the complete synchronization process is verified by measurements using the test hardware.
Performance Prediction and Verification for Bistatic SAR Synchronization Link
2006 ; Dresden, Germany
2006-05-17
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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