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Open AccessArticle
A Novel SAR Imaging Method for GEO Satellite–Ground Bistatic SAR System with Severe Azimuth Spectrum Aliasing and 2-D Spatial Variability
by
Jingjing Ti
Jingjing Ti 1,
Zhiyong Suo
Zhiyong Suo 1,*,
Yi Liang
Yi Liang 1,
Bingji Zhao
Bingji Zhao 2 and
Jiabao Xi
Jiabao Xi 1
1
National Key Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China
2
Beijing Institute of Spacecraft System Engineering, Beijing 100094, China
*
Author to whom correspondence should be addressed.
Remote Sens. 2024, 16(15), 2853; https://doi.org/10.3390/rs16152853 (registering DOI)
Submission received: 20 April 2024
/
Revised: 31 July 2024
/
Accepted: 1 August 2024
/
Published: 3 August 2024
Abstract
The satellite–ground bistatic configuration, which uses geosynchronous synthetic aperture radar (GEO SAR) for illumination and ground equipment for reception, can achieve wide coverage, high revisit, and continuous illumination of interest areas. Based on the analysis of the signal characteristics of GEO satellite–ground bistatic SAR (GEO SG-BiSAR), it is found that the bistatic echo signal has problems of azimuth spectrum aliasing and 2-D spatial variability. Therefore, to overcome those problems, a novel SAR imaging method for a GEO SG-BiSAR system with severe azimuth spectrum aliasing and 2-D spatial variability is proposed. Firstly, based on the geometric configuration of the GEO SG-BiSAR system, the time-domain and frequency-domain expressions of the signal are derived in detail. Secondly, in order to avoid the increasing cost caused by traditional multi-channel reception technology and the processing burden caused by inter-channel errors, the azimuth deramping is executed to solve the azimuth spectrum aliasing of the signal under the special geometric structure of GEO SG-BiSAR. Thirdly, based on the investigation of azimuth and range spatial variability characteristics of GEO SG-BiSAR in the Range Doppler (RD) domain, the azimuth spatial variability correction strategy is proposed. The signal corrected by the correction strategy has the same migration characteristics as monostatic radar. Therefore, the traditional chirp scaling function (CSF) is also modified to solve the range spatial variability of the signal. Finally, the two-dimensional spectrum of GEO SG-BiSAR with modified chirp scaling processing is derived, followed by the SPECAN operation to obtain the focused SAR image. Furthermore, the completed flowchart is also given to display the main composed parts for GEO SG-BiSAR imaging. Both azimuth spectrum aliasing and 2-D spatial variability are taken into account in the imaging method. The simulated data and the real data obtained by the Beidou navigation satellite are used to verify the effectiveness of the proposed method.
Share and Cite
MDPI and ACS Style
Ti, J.; Suo, Z.; Liang, Y.; Zhao, B.; Xi, J.
A Novel SAR Imaging Method for GEO Satellite–Ground Bistatic SAR System with Severe Azimuth Spectrum Aliasing and 2-D Spatial Variability. Remote Sens. 2024, 16, 2853.
https://doi.org/10.3390/rs16152853
AMA Style
Ti J, Suo Z, Liang Y, Zhao B, Xi J.
A Novel SAR Imaging Method for GEO Satellite–Ground Bistatic SAR System with Severe Azimuth Spectrum Aliasing and 2-D Spatial Variability. Remote Sensing. 2024; 16(15):2853.
https://doi.org/10.3390/rs16152853
Chicago/Turabian Style
Ti, Jingjing, Zhiyong Suo, Yi Liang, Bingji Zhao, and Jiabao Xi.
2024. "A Novel SAR Imaging Method for GEO Satellite–Ground Bistatic SAR System with Severe Azimuth Spectrum Aliasing and 2-D Spatial Variability" Remote Sensing 16, no. 15: 2853.
https://doi.org/10.3390/rs16152853
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