Space-Surface Bistatic SAR Image Enhancement Based on Repeat-Pass Coherent Fusion With Beidou-2/Compass-2 as Illuminators

• Published in: IEEE geoscience and remote sensing letters Vol. 13; no. 12; pp. 1832 - 1836
• Main Authors: Zeng, Tao, Zhang, Tian, Tian, Weiming, Hu, Cheng
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.12.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: BeiDou Navigation Satellite System; Beidou-2/Compass-2; Coherence; coherent fusion; Geosynchronous orbits; Global navigation satellite system; Illuminators; Image enhancement; Image quality; Image resolution; Imagery; Imaging; Navigation; Navigation satellites; Navigation systems; passive SAR; SAR (radar); Satellite broadcasting; Satellite imagery; Satellite navigation systems; Satellites; Signal processing; Signal to noise ratio; space-surface bistatic SAR (SS-BiSAR); Spaceborne remote sensing; Synthetic aperture radar; synthetic aperture radar (SAR)
• ISSN: 1545-598X; 1558-0571
• DOI: 10.1109/LGRS.2016.2614337

Low signal power density limits the performance of space-surface bistatic synthetic aperture radar (SS-BiSAR) using Global Navigation Satellite System (GNSS) satellites as illuminators. To tackle this problem, in this letter, a novel bistatic SAR image enhancement technique based on repeat-pass coherent fusion is proposed. The works in this letter include three aspects. First, repeat-pass experiments are designed to ensure the best resolution. Second, a modified CLEAN technique is applied to remove the direct signal interference from the focused BiSAR images. Third, a coherence-processing method is proposed to implement coherence of each repeat-pass BiSAR image and then they are coherently fused to obtain a quality-improved BiSAR image. Twenty-two days of repeat-pass BiSAR experiments with Beidou-2/Compass-2 inclined geosynchronous orbit satellites as illuminators have been designed and conducted. The data were processed by the proposed method. The results show that the method can obtain better image quality compared with the traditional noncoherent fusion method and the single-day imaging result, which validates the proposed method and proves the huge potential in realizing local area monitoring with SS-BiSAR using GNSS satellites as illuminators.