The Effects of Orbital Perturbation on Geosynchronous Synthetic Aperture Radar Imaging

Jiang, Mian; Hu, Wen-Long; Ding, Chibiao; Liu, Ge

doi:10.1109/lgrs.2014.2385101

Cited by 21 publications

(6 citation statements)

References 8 publications

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“…The simulated data and real data are used to validate the proposed method. The simulation experiments are implemented based on the system parameters of GEO SAR in Table I [20], and the micro-motion parameters of a ship are listed in Table II. The simulated data can reflect the high-order slant range and the micro-motion of the target to a certain degree.…”

Section: Experimental Results and Analysismentioning

confidence: 99%

Signal Separation in GEO SAR Imaging of Maneuvering Ships by Removing Micro-Motion Effect

Guo

et al. 2022

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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P is totally removed and the blue curve becomes flat. However, due to mismatching, the signal of B P is still modulated by the micro-motion and the red curve in Fig. 3(c) fluctuates. If Fourier transform is directly performed on A P in the azimuth direction after micro-motion compensation, the imaging result of A P will be degraded because of the interference caused by micro-motion of B P , as shown in Fig. 3(d). Therefore, signal separation must be performed by removing the micro-motion effect to guarantee the imaging quality. III. BASIC IDEA OF SIGNAL SEPARATIONSince the time-frequency characteristics of various scatterers are different, imaging needs to be performed scatterer by scatterer.

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Section: Experimental Results and Analysismentioning

confidence: 99%

Signal Separation in GEO SAR Imaging of Maneuvering Ships by Removing Micro-Motion Effect

Guo

et al. 2022

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…In the 1800 s of synthetic aperture time, the fifth diagonal model can meet the requirements. Using Taylor series expansion in azimuth time, the slant range is extended to a fifth-order model by following equation:

‖ boldnormal R (t_{a}) ‖ = R_{c} + V_{c} t_{a} + \frac{1}{2} A_{c} t_{a}^{2} + \frac{1}{6} B_{c} t_{a}^{3} + \frac{1}{24} C_{c} t_{a}^{4} + \frac{1}{120} D_{c} t_{a}^{5} + \dots

where, the expression of

R_{c}, V_{c}, A_{c}, B_{c}, C_{c}

can be obtained in [31]. The value of

D_{c}

can be further expressed as:

D_{c} = false(15 x_{1}^{5} / 32 - 75 x_{1}^{3} x_{2} / 4 + 45 x_{3} x_{1}^{2} / 2 + 45 x_{1} x_{2}^{2} / 2 - 30 x_{4} x_{1} - 30 x_{3} x_{2} + 60 x_{5} false) R_{S T}

in which:…”

Section: Signal Model For Geo Sar Staring Observationmentioning

confidence: 99%

“…As indicated in [31], the satellite and target kinematic parameters that can be obtained from the orbital elements include the following:

a

, i.e., the semimajor axis of the orbit,

e

, i.e., the eccentricity of the orbit,

i

, i.e., the inclination of the orbit, and Ω , i.e., the longitude of the ascending node,

f

, i.e., the true anomaly,

w

, i.e., the argument of perigee. Ignoring the slight stochastic perturbation errors, the osculating orbital elements can be expressed as:

{\begin{matrix} a = a_{m} + {(normalΔ a)}_{s e c} + {(normalΔ a)}_{l p} + {(normalΔ a)}_{s p} \\ e = e_{m} + {(normalΔ e)}_{s e c} + {(normalΔ e)}_{l p} + {(normalΔ e)}_{s p} \\ i = i_{m} + {(normalΔ i)}_{s e c} + {(normalΔ i)}_{l p} + {(normalΔ i)}_{s p} \\ Ω = Ω_{m} + {(normalΔ Ω)}_{s e c} + {(normalΔ Ω)}_{l p} + {(normalΔ Ω)}_{s p} \\ f = f_{m} + {(normalΔ f)}_{s e c} + {(normalΔ f)}_{l p} + {(normalΔ f)}_{s p} \\ w = w_{m} + {(normalΔ w)}_{s e c} + {(normalΔ w)}_{l p} + (normalΔ w) \end{matrix}

…”

Section: Signal Model For Geo Sar Staring Observationmentioning

confidence: 99%

A Generalized Chirp-Scaling Algorithm for Geosynchronous Orbit SAR Staring Observations

2017

Sensors

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Geosynchronous Orbit Synthetic Aperture Radar (GEO SAR) has recently received increasing attention due to its ability of performing staring observations of ground targets. However, GEO SAR staring observation has an ultra-long integration time that conventional frequency domain algorithms cannot handle because of the inaccurately assumed slant range model and existing azimuth aliasing. To overcome this problem, this paper proposes an improved chirp-scaling algorithm that uses a fifth-order slant range model where considering the impact of the “stop and go” assumption to overcome the inaccuracy of the conventional slant model and a two-step processing method to remove azimuth aliasing. Furthermore, the expression of two-dimensional spectrum is deduced based on a series of reversion methods, leading to an improved chirp-scaling algorithm including a high-order-phase coupling function compensation, range and azimuth compression. The important innovations of this algorithm are implementation of a fifth-order order slant range model and removal of azimuth aliasing for GEO SAR staring observations. A simulation of an L-band GEO SAR with 1800 s integration time is used to demonstrate the validity and accuracy of this algorithm.

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“…These forces could cause temporal variations in the orbital elements and lead to sustained orbital variation and drift, further affecting the SAR movement relative to Earth. In the LEOSAR, orbital perturbations influence little on the Doppler frequency modulation rate (DFMR) and beam-crossing velocity [31]. Correspondingly, the variation in the associated azimuthal resolution is trivial.…”

Section: Introductionmentioning

confidence: 99%

On Azimuthal Resolution of the Lunar-Based SAR Under the Orbital Perturbation Effects

Chen

Guo

2023

IEEE Trans. Geosci. Remote Sensing

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This paper studies the orbital perturbation effects on the azimuthal resolution in lunar-based synthetic aperture radar (LBSAR). We derive explicit expressions for the Doppler frequency modulation rate (DFMR) and beam-crossing velocity using the antenna beam pointing and orbit models. Following that, the azimuthal resolution is expressed in line with orbital elements and SAR configurations. The results show that the long-term orbital variations caused by accumulated perturbation effects significantly affect the azimuthal resolution, which, in effect, produces aperiodic variations in the azimuthal resolution. Such a phenomenon is most distinguished for a large LBSAR look angle, leading to a fluctuation of over 30% or even larger in the azimuthal resolution across different cycles. Additionally, the errors give rise by short-term orbital perturbations could impact azimuthal resolution to a lesser extent, with corresponding fluctuations consistently below 3%. The findings reveal that it is imperative to consider the irregular variability of azimuthal resolution due to orbital perturbations in the LBSAR.

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The Effects of Orbital Perturbation on Geosynchronous Synthetic Aperture Radar Imaging

Cited by 21 publications

References 8 publications

Signal Separation in GEO SAR Imaging of Maneuvering Ships by Removing Micro-Motion Effect

Signal Separation in GEO SAR Imaging of Maneuvering Ships by Removing Micro-Motion Effect

A Generalized Chirp-Scaling Algorithm for Geosynchronous Orbit SAR Staring Observations

On Azimuthal Resolution of the Lunar-Based SAR Under the Orbital Perturbation Effects

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