Abstract
Spaceborne synthetic aperture radar (SAR) missions operating at low frequencies, such as L-band or P-band, are significantly influenced by the ionosphere. As one of the serious ionosphere effects, Faraday rotation (FR) is a remarkable distortion source for the polarimetric SAR (PolSAR) application. Various published FR estimators along with an improved one have been introduced to solve this issue, all of which are implemented by processing a set of PolSAR real data. The improved estimator exhibits optimal robustness based on performance analysis, especially in term of the system noise. However, all published estimators, including the improved estimator, suffer from a potential FR angle (FRA) ambiguity. A novel strategy of the ambiguity correction for those FR estimators is proposed and shown as a flow process, which is divided into pixel-level and image-level correction. The former is not yet recognized and thus is considered in particular. Finally, the validation experiments show a prominent performance of the proposed strategy.
Highlights
There is a growing trend in low-frequency synthetic aperture radar (SAR) systems for Earth observation, these systems are seriously affected by the ionosphere effects, such as group delay, phase advance, dispersion, scintillation, and Faraday rotation (FR) [1,2,3,4]
FR is generally known as a potential complication in the spaceborne polarimetric synthetic aperture radar (PolSAR) survey
Experimental results indicate that the performance of the improved estimator is generally not affected by system noise, and when true FR angle (FRA) is less than 44◦, the improved estimator maintains the bias to 0◦
Summary
There is a growing trend in low-frequency synthetic aperture radar (SAR) systems for Earth observation, these systems are seriously affected by the ionosphere effects, such as group delay, phase advance, dispersion, scintillation, and Faraday rotation (FR) [1,2,3,4]. FR is generally known as a potential complication in the spaceborne polarimetric synthetic aperture radar (PolSAR) survey. At low frequencies, such as L-band and P-band, it becomes a more serious and non-negligible impact on polarimetric measurements [5,6,7,8,9,10]. Sensors 2018, 18, 1158 identities tends to be masked by system noise and phase unwrapping is generally lack of a baseline, but the FRA prediction, which can be renamed to image-level correction, is the most effective method for FRA ambiguity correction. The paper aims to introduce an improved estimator and a novel strategy of FRA ambiguity correction for FR estimators, which is organized as follows.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
