An imaging algorithm based on keystone transform for one-stationary bistatic SAR of spotlight mode

Xiaolan Qiu,Holger Nies,Lijia Huang,Donghui Hu,Chibiao Ding,Otmar Loffeld,Florian Behner,Simon Reuter

doi:10.1186/1687-6180-2012-221

Abstract

This article proposes an imaging algorithm based on Keystone Transform for bistatic SAR with a stationary receiver. It can efficiently be applied to high-resolution spotlight mode, and can directly be process the bistatic SAR data which have been ranged compressed by the synchronization reference pulses. Both simulation and experimental results validate the good performance of this algorithm.

Highlights

Bistatic SAR is more flexible in data acquisition geometry compared with traditional monostatic SAR
Among the various configurations of bistatic SAR, the so-called one-stationary configuration, which is usually formed by an existing moving transmitter and a stationary passive receiver, is, in the authors’ opinion, one of the most practical configurations
We propose to use the Keystone Transform for bistatic SAR imaging

Summary

Introduction

Bistatic SAR is more flexible in data acquisition geometry compared with traditional monostatic SAR. The approximation in the above equation cohmes fromi omitting of the phase difference between h i rect τ ÀRD ðηÞ=c T expfÀjφRðη þ τÞg and rect τ ÀRbi ðη;rÞ=c T expfÀjφRðη þ τÞg, which can usually be ignored It can be seen from Equation (9) that, after range compression using the reference signal from the direct channel, the time synchronization problem is solved because all the received echo pulses are aligned to the known RD (η). In the spaceborne-ground bistatic SAR configuration, such as in TerraSAR-X/HITCHHIKER experiment, the original Doppler bandwidth is about 5192 Hz, but after the range compression using the direct pulses, the residual Doppler bandwidth shrinks to be about 62 Hz. if traditional imaging algorithms, which correct RCM in the azimuth frequency domain, are applied, a Doppler wideband signal rebuilding step should be adopted, which makes them not very convenient to use. The RCM, which is within half a slant range resolution cell ρr, can Figure 2 Block diagram of the proposed algorithm for one-stationary bistatic SAR of spotlight mode

9.65 GHz fB

Conclusion