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Suppressing Paired Echoes Caused by Stair-Step Antenna Steering in TOPS SAR Imaging

College of Electronic Science and Technology, National University of Defense Technology, No. 109 De Ya Road, Changsha 410073, China
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Remote Sens. 2019, 11(21), 2544; https://doi.org/10.3390/rs11212544
Received: 16 October 2019 / Accepted: 25 October 2019 / Published: 29 October 2019
(This article belongs to the Section Remote Sensing Image Processing)
The use of electronically steered antennas in the azimuth dimension typically leads to a staircase-like antenna beam steering law in the Terrain Observation by Progressive Scan (TOPS) wide-swath synthetic aperture radar (SAR) data acquisition mode, which will introduce paired echoes in the focused images. This paper proposes a new approach for removing such paired echoes from TOPS SAR images based on the generalization of the ideal optimum filtering concept, which can be implemented easily in the SAR data processing. Modeling the amplitude-modulated azimuth signal shows that the absolute phase of the introduced paired echoes cannot be determined due to the random rotation angle jump time for each target, which will prevent the precise use of optimum filtering. An extended optimum filtering approach, which is originally proposed for suppressing the azimuth ambiguities in SAR images, is reintroduced in this particular case, and a new approximated and generalized form of the deconvolving filtering in the approach is redefined to accommodate the undetermined phase for both the strongest paired distortion peaks and the other peripheral peaks in the distorted impulse response function (IRF). Simulated data from a TOPS SAR mode with staircase-like beam steering are used to verify the improvement in image quality by using the new method. View Full-Text
Keywords: synthetic aperture radar (SAR); terrain observation by progressive scan (TOPS); staircase antenna beam steering; paired echo; optimum filtering synthetic aperture radar (SAR); terrain observation by progressive scan (TOPS); staircase antenna beam steering; paired echo; optimum filtering
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MDPI and ACS Style

He, F.; Zhang, Y.; Yi, T.; Jin, G.; Dong, Z. Suppressing Paired Echoes Caused by Stair-Step Antenna Steering in TOPS SAR Imaging. Remote Sens. 2019, 11, 2544.

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