Using GNSS Signals as a Proxy for SAR Signals: Correcting Ionospheric Defocussing

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Using GNSS Signals as a Proxy for SAR Signals: Correcting Ionospheric Defocussing. / Mannix, Chris; Belcher, David; Cannon, P.S.; Angling, Matthew.

In: Radio Science, Vol. 51, No. 2, 03.02.2016, p. 60-70.

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@article{df4eb0394bf9499886fbd8ab1bf97fe2,
title = "Using GNSS Signals as a Proxy for SAR Signals: Correcting Ionospheric Defocussing",
abstract = "Ultrahigh frequency space-based synthetic aperture radar (SAR) can suffer from the degrading effects of a scintillating ionosphere which modulates both the phase and the amplitude of the radar signal. In this paper, we use Global Navigation Satellite System (GNSS) signals to synthesize an L-band SAR point spread function (PSF). The process of transforming the GNSS signal to the equivalent SAR PSF is described. The synthesized PSF is used to explore the possibility of using a phase correction determined from a point target in a SAR image to correct the ionospheric degradation. GNSS data recorded on equatorial Ascension Island during scintillation events are used to test the feasibility of this approach by applying a phase correction to one GNSS receiver from another located along a magnetic east-west baseline. The peak-to-sidelobe ratios of the synthesized L-band SAR point spread functions before and after the correction are compared, and it is shown that this approach improves the L-band PSF over distances of ~3000 m in the ionosphere, corresponding to 6000 m on the ground.",
keywords = "GPS, ionosphere, SAR",
author = "Chris Mannix and David Belcher and P.S. Cannon and Matthew Angling",
year = "2016",
month = feb,
day = "3",
doi = "10.1002/2015RS005822",
language = "English",
volume = "51",
pages = "60--70",
journal = "Radio Science",
issn = "0048-6604",
publisher = "American Geophysical Union",
number = "2",

}

RIS

TY - JOUR

T1 - Using GNSS Signals as a Proxy for SAR Signals: Correcting Ionospheric Defocussing

AU - Mannix, Chris

AU - Belcher, David

AU - Cannon, P.S.

AU - Angling, Matthew

PY - 2016/2/3

Y1 - 2016/2/3

N2 - Ultrahigh frequency space-based synthetic aperture radar (SAR) can suffer from the degrading effects of a scintillating ionosphere which modulates both the phase and the amplitude of the radar signal. In this paper, we use Global Navigation Satellite System (GNSS) signals to synthesize an L-band SAR point spread function (PSF). The process of transforming the GNSS signal to the equivalent SAR PSF is described. The synthesized PSF is used to explore the possibility of using a phase correction determined from a point target in a SAR image to correct the ionospheric degradation. GNSS data recorded on equatorial Ascension Island during scintillation events are used to test the feasibility of this approach by applying a phase correction to one GNSS receiver from another located along a magnetic east-west baseline. The peak-to-sidelobe ratios of the synthesized L-band SAR point spread functions before and after the correction are compared, and it is shown that this approach improves the L-band PSF over distances of ~3000 m in the ionosphere, corresponding to 6000 m on the ground.

AB - Ultrahigh frequency space-based synthetic aperture radar (SAR) can suffer from the degrading effects of a scintillating ionosphere which modulates both the phase and the amplitude of the radar signal. In this paper, we use Global Navigation Satellite System (GNSS) signals to synthesize an L-band SAR point spread function (PSF). The process of transforming the GNSS signal to the equivalent SAR PSF is described. The synthesized PSF is used to explore the possibility of using a phase correction determined from a point target in a SAR image to correct the ionospheric degradation. GNSS data recorded on equatorial Ascension Island during scintillation events are used to test the feasibility of this approach by applying a phase correction to one GNSS receiver from another located along a magnetic east-west baseline. The peak-to-sidelobe ratios of the synthesized L-band SAR point spread functions before and after the correction are compared, and it is shown that this approach improves the L-band PSF over distances of ~3000 m in the ionosphere, corresponding to 6000 m on the ground.

KW - GPS

KW - ionosphere

KW - SAR

U2 - 10.1002/2015RS005822

DO - 10.1002/2015RS005822

M3 - Article

VL - 51

SP - 60

EP - 70

JO - Radio Science

JF - Radio Science

SN - 0048-6604

IS - 2

ER -