Abstract
High-quality focusing with accurate phase-preserving is a significant and challenging step in interferometric synthetic aperture radar (InSAR) imaging. Compared with conventional frequency-based imaging algorithms, the time-domain back-projection algorithm (TDBPA) can greatly ensure the accuracy of imaging and phase-preserving by point-to-point coherent integration but suffers from huge computational complexity. In this paper, we propose an efficient InSAR imaging method, called a frequency-domain back-projection algorithm (FDBPA), to achieve high-resolution focusing and accurate phase-preserving of InSAR imaging. More specifically, FDBPA is utilized to replace the traditional point-to-point coherent integration of TDBPA with frequency-domain transform. It divides the echo spectrum into uniform grids and transforms the range compression data into the range frequency domain. Phase compensation and non-uniform Fourier transform of the underlying scene are implemented to achieve image focusing in the wavenumber domain. Then, the interferometric phase of the target scene can be preserved by accurate phase compensation of the target’s distance. FDBPA avoids the repetitive calculation of index values and point-to-point coherent integration which reduces the time complexity compared with TDBPA. The characteristics of focusing and phase-preserving of our method are analyzed via simulations and experiments. The results demonstrate the efficiency and high-quality imaging of the FDBPA method. It can improve the imaging efficiency by more than three times, while keeping similar imaging accuracy compared with TDBPA.
Highlights
Synthetic aperture radar (SAR) [1,2,3,4,5,6] is a breakthrough in the field of modern remote-sensing science
In Reference [42], an efficient three-dimensional imaging method based on frequency-domain back-projection algorithm (FDBPA) is proposed for SAR imaging, the results demonstrate the great improvement of imaging efficiency
To compare the performance of the proposed algorithm with several classical imaging algorithms, the simulation data are processed by imaging algorithms based on time-domain back-projection algorithm (TDBPA), FDBPA, range-Doppler algorithm (RDA), and fast factorized back-projection algorithm (FFBPA), respectively
Summary
Synthetic aperture radar (SAR) [1,2,3,4,5,6] is a breakthrough in the field of modern remote-sensing science. Due to the influences of airflow, obstacles, and other factors, the movement trajectory of the radar platform usually is complex and deviates greatly from the ideal trajectory in practice It increases the difficulty of frequency-domain focusing, resulting in a decrease in imaging accuracy and phase extraction accuracy. Different from the frequency-domain-based algorithms, time-domain back-projection algorithm (TDBPA) is more suitable for SAR high-resolution imaging in the case of the complex trajectory of the platform, because it can provide precise focusing and phase information of a large scene by point-to-point coherent integration without any assumption constrained. To improve imaging efficiency of TDBPA, some efficient modified TDBP methods based on sub-aperture decomposition and scene segmentation, such as the fast factorized back-projection algorithm (FFBPA) [34,35,36,37,38,39], have been proposed for SAR imaging. The conclusions and future work are illustrated in the sixth section
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