Phase synchronization and doppler centroid estimation in fixed receiver bistatic SAR systems

Journal article (2008)

Authors

Paco López-Dekker Laboratory Geoscience and Remote Sensing , Mathematical Geodesy and Positioning - CEG , Universitat Politecnica de Catalunya
Jordi J. Mallorquí Universitat Politecnica de Catalunya
Pau Serra-Morales Universitat Politecnica de Catalunya
Jesús Sanz-Marcos Estudio Cota Cero
Research Group
Mathematical Geodesy and Positioning (CEG) (TU Delft)
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Published Date

2008-11

Language

English

Reuse Rights

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Faculty

Civil Engineering & Geosciences

Department

Geoscience and Remote Sensing

Research Group

Mathematical Geodesy and Positioning

Abstract

This paper discusses temporal and phase synchronization in bistatic synthetic aperture radar (SAR) systems that use orbital sensors as coherent sources of opportunity and receivers at a fixed location. The discussion is particularized to SAR Bistatic Receiver for INterferometric Applications (SABRINA), a ground-based bistatic receiver that uses ENVISAT and ERS-2 as transmitters. Transmitter-receiver synchronization is hindered by the presence of independent reference oscillators at the transmit and receive end and by the lack of a common time frame. Phase synchronization and pulse alignment are achieved using a dedicated channel that receives a clean signal directly from the satellite. How to align the acquired data with the satellite orbit and how to estimate the Doppler centroid (DC) are studied. It is shown that in the bistatic configuration considered, the receiver provides an implicit control point which limits the negative impact of a DC misestimation on the resulting images. An algorithm to achieve this temporal alignment using the apparent phase history of the received pulses is proposed. Finally, this algorithm is validated through Monte Carlo simulations and experimental data acquired by SABRINA.