Vibration Compensation of Airborne Terahertz SAR Based on Along Track Interferometry

Sun, Jinping; Hao, Zhaoxin; Li, Qing; Li, Daojing

doi:10.1109/lgrs.2021.3116677

Cited by 12 publications

(5 citation statements)

References 14 publications

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“…In recent years, terahertz synthetic aperture radar (THz SAR) has attracted more and more attention due to its high imagery resolution and strong anti-jamming ability. The frequency range of the terahertz wave covers from 0.1THz to 10THz, which is between the microwave and infrared ray [6]- [11]. THz SAR makes it easier to obtain high-resolution imaging results, but it is suffering from the problem of the high-frequency vibration of the platform, which can defocus the imaging results.…”

Section: Nomenclaturementioning

confidence: 99%

Compensation for High-Frequency Vibration of SAR Imaging in the Terahertz Band Based on Linear Chirplet Transform and Empirical Mode Decomposition

Chen

Wang

Zhang

2023

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

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Synthetic aperture radar (SAR) in Terahetz (THz) band is very important and valuable in the field of radar signal processing, and it is much sensitive to the high-frequency vibration of the platform due to the short wavelength. In this paper, the high-frequency vibration is characterized as multi-component sinusoidal frequency modulated (SFM) signal, and the parameters estimation method based on the linear chirplet transform (LCT) and empirical mode decomposition (EMD) is proposed to compensate the high-frequency vibration errors. This method can extract the instantaneous frequency (IF) of the received signal with high precision, and the focused SAR image can be obtained consequently. Results of simulated and real measured data are provided to illustrate the effectiveness of the novel algorithm proposed in this paper.

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Section: Nomenclaturementioning

confidence: 99%

Compensation for High-Frequency Vibration of SAR Imaging in the Terahertz Band Based on Linear Chirplet Transform and Empirical Mode Decomposition

Chen

Wang

Zhang

2023

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

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“…The simulation method is the same as that in Refs. [22,23]. In the echo simulation, the vibration errors with the same parameters as that in Section 6.2 are added.…”

Section: Simulation Results Of Distributed Imaging Scenementioning

confidence: 99%

“…The component of high-frequency vibration along the line of sight (LOS) is the main factor affecting the signal phase according to (6). Hence, the calculation can be simplified by setting C to 1 without affecting the accuracy of the result [23].…”

Section: Thz-sar High-frequency Vibration Error Model and Effectmentioning

confidence: 99%

Estimation of High-Frequency Vibration Parameters for Airborne Terahertz SAR Using Chirplet Decomposition and LS Sequential Estimators

Hao

Sun

et al. 2022

Remote Sensing

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Due to the short wavelength of the terahertz wave, airborne terahertz synthetic aperture radar (THz-SAR) suffers from echo phase errors caused by the high-frequency vibration of the platform. These errors will result in defocusing and the emergence of ghost targets, which will degrade the quality of the image. Therefore, it is necessary to compensate for phase errors in order to bring the image into focus. This paper proposes a multi-component high-frequency vibration parameter estimation method based on chirplet decomposition and least squares (LS) sequential estimators, which differs from other methods that can only be applied to simple harmonic vibrations. In particular, we first obtain the instantaneous chirp rate (ICR) of the signal by chirplet decomposition. Then, we employ the LS sequential estimators in conjunction with separable regression technique (SRT) to estimate vibration parameters. The estimated parameters are subsequently used to re-establish the ICR components for each vibration component and these parameters are further re-estimated to improve their accuracy. Based on the estimated parameters, phase compensation functions can be constructed to suppress the defocusing and ghost targets in airborne THz-SAR imaging. Simulated results on point targets and distributed imaging scenes demonstrate that the proposed method is accurate and reliable even at low signal-to-noise ratios (SNRs).

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“…Micro-Doppler feature extraction and parameter estimation are important issues in vibrating target detection of synthetic aperture radar (SAR), which can mainly be classified into three types of methods based on the image domain, timefrequency analysis and transform domain. Image-domain-based micro-Doppler feature extraction and parameter estimation methods mainly take advantage of the high-resolution capability of synthetic aperture radar to extract the radial micromotion history of the scattering center of the vibrating target with a one-dimensional high-resolution distancedirected sequence [9]. Time-frequency analysis is mainly divided into linear time-frequency analysis, bilinear time-frequency analysis and high-order time-frequency analysis.…”

Section: Introductionmentioning

confidence: 99%

An Airborne Arc Array Synthetic Aperture Radar Vibration Error Compensation Method

Xiao,

Huang,

et al. 2024

Sensors

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Compared to conventional radars, arc array synthetic aperture radar (SAR) enables wide-area observation under ideal conditions. However, helicopters carrying arc array SAR platforms are generally smaller in size and more sensitive to vibration, which has a greater impact on the imaging quality. In this paper, the vibration error of the arc array SAR platform is investigated, and a vibration error model of the arc array SAR platform is established. Based on the study of the vibration error model, a vibration phase estimation and compensation algorithm based on the delayed conjugate multiplication method is proposed. In the first step, distance pulse pressure processing is performed on the echo signal. In the second step, the pulse pressure signals and their delays in the same distance unit are subjected to conjugate multiplication, and the phase of the signal after conjugate multiplication is extracted. The extracted phase is then amplitude- and phase-compensated to estimate the vibration phase. In the third step, the vibration phase is compensated in the azimuthal direction of the distance pulse pressure signal, and the pairwise echo is eliminated, which completes the compensation of the airborne arc array SAR vibration platform.

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Vibration Compensation of Airborne Terahertz SAR Based on Along Track Interferometry

Cited by 12 publications

References 14 publications

Compensation for High-Frequency Vibration of SAR Imaging in the Terahertz Band Based on Linear Chirplet Transform and Empirical Mode Decomposition

Compensation for High-Frequency Vibration of SAR Imaging in the Terahertz Band Based on Linear Chirplet Transform and Empirical Mode Decomposition

Estimation of High-Frequency Vibration Parameters for Airborne Terahertz SAR Using Chirplet Decomposition and LS Sequential Estimators

An Airborne Arc Array Synthetic Aperture Radar Vibration Error Compensation Method

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