Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle

Synthetic Aperture Radar (SAR) imaging with a non-zero (forward) squint angle is capable of providing a longer time for reaction than that of the broadside mode. However, due to the large squint angle, there will be severe coupling between range and azimuth samples in the echoed data, which is known...

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Main Authors: Yang, Lei, Zhou, Song, Zhao, Lifan, Xing, Mengdao
Other Authors: School of Electrical and Electronic Engineering
Format: Article
Language:English
Published: 2018
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Online Access:https://hdl.handle.net/10356/86580
http://hdl.handle.net/10220/45328
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-865802020-03-07T13:57:29Z Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle Yang, Lei Zhou, Song Zhao, Lifan Xing, Mengdao School of Electrical and Electronic Engineering Auto-calibration Squint Synthetic Aperture Radar (SAR) Synthetic Aperture Radar (SAR) imaging with a non-zero (forward) squint angle is capable of providing a longer time for reaction than that of the broadside mode. However, due to the large squint angle, there will be severe coupling between range and azimuth samples in the echoed data, which is known as the problematic Range Cell Migration (RCM) in the SAR community. Especially when the SAR sensor mounted on an airborne platform encounters unexpected motion deviations/errors, the coupling becomes more complicated, and it is difficult to differentiate the systematic RCM for the SAR Image Formation Processing (IFP) and the non-systematic RCM error to be compensated. To this end, a novel and accurate SAR imaging algorithm is proposed in this paper to facilitate the processing of airborne SAR data collected at a high-squint angle. Firstly, the proposed algorithm is established under a Fast Time-Domain Back-Projection (FTDBP) framework for the SAR IFP. FTDBP paves the way to avoid the complicated processing for the systematic RCM as for the conventional SAR IFP in the Doppler processing manner. It is capable of generating a high-resolution SAR image efficiently under more general geometries and configurations. Secondly, regarding the non-systematic RCM errors, the proposed algorithm realizes the compensation by correcting both the Non-systematic Range Cell Migration (NsRCM), as well as Azimuthal Phase Error (APE) in a coherent manner. It is consequently capable of auto-calibrating the effects of the motion error completely without being dependent on the airborne navigation unit. Finally, both simulated and raw data collected by the airborne squinted SAR are applied to evaluate the proposed algorithm. Comparisons with conventional algorithms are carried out to reveal the superiority of the proposed algorithm. Published version 2018-07-27T07:56:49Z 2019-12-06T16:25:10Z 2018-07-27T07:56:49Z 2019-12-06T16:25:10Z 2018 Journal Article Yang, L., Zhou, S., Zhao, L., & Xing, M. (2018). Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle. Remote Sensing, 10(2), 321-. 2072-4292 https://hdl.handle.net/10356/86580 http://hdl.handle.net/10220/45328 10.3390/rs10020321 en Remote Sensing © 2018 The Author(s). Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 21 p. application/pdf
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic Auto-calibration
Squint Synthetic Aperture Radar (SAR)
spellingShingle Auto-calibration
Squint Synthetic Aperture Radar (SAR)
Yang, Lei
Zhou, Song
Zhao, Lifan
Xing, Mengdao
Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle
description Synthetic Aperture Radar (SAR) imaging with a non-zero (forward) squint angle is capable of providing a longer time for reaction than that of the broadside mode. However, due to the large squint angle, there will be severe coupling between range and azimuth samples in the echoed data, which is known as the problematic Range Cell Migration (RCM) in the SAR community. Especially when the SAR sensor mounted on an airborne platform encounters unexpected motion deviations/errors, the coupling becomes more complicated, and it is difficult to differentiate the systematic RCM for the SAR Image Formation Processing (IFP) and the non-systematic RCM error to be compensated. To this end, a novel and accurate SAR imaging algorithm is proposed in this paper to facilitate the processing of airborne SAR data collected at a high-squint angle. Firstly, the proposed algorithm is established under a Fast Time-Domain Back-Projection (FTDBP) framework for the SAR IFP. FTDBP paves the way to avoid the complicated processing for the systematic RCM as for the conventional SAR IFP in the Doppler processing manner. It is capable of generating a high-resolution SAR image efficiently under more general geometries and configurations. Secondly, regarding the non-systematic RCM errors, the proposed algorithm realizes the compensation by correcting both the Non-systematic Range Cell Migration (NsRCM), as well as Azimuthal Phase Error (APE) in a coherent manner. It is consequently capable of auto-calibrating the effects of the motion error completely without being dependent on the airborne navigation unit. Finally, both simulated and raw data collected by the airborne squinted SAR are applied to evaluate the proposed algorithm. Comparisons with conventional algorithms are carried out to reveal the superiority of the proposed algorithm.
author2 School of Electrical and Electronic Engineering
author_facet School of Electrical and Electronic Engineering
Yang, Lei
Zhou, Song
Zhao, Lifan
Xing, Mengdao
format Article
author Yang, Lei
Zhou, Song
Zhao, Lifan
Xing, Mengdao
author_sort Yang, Lei
title Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle
title_short Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle
title_full Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle
title_fullStr Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle
title_full_unstemmed Coherent auto-calibration of APE and NsRCM under fast back-projection image formation for airborne SAR imaging in highly-squint angle
title_sort coherent auto-calibration of ape and nsrcm under fast back-projection image formation for airborne sar imaging in highly-squint angle
publishDate 2018
url https://hdl.handle.net/10356/86580
http://hdl.handle.net/10220/45328
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