A Fast High-Resolution Imaging Algorithm for Helicopter-Borne Rotating Array SAR Based on 2-D Chirp-Z Transform

Qin, Mengyi; Liu, Dong; Tang, Xianhui; Zeng, Cao; Li, Wenjun; Xu, Li

doi:10.3390/rs11141669

Cited by 7 publications

(6 citation statements)

References 17 publications

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“…An appropriate constant factor ϕ is chosen to make the remaining Doppler bandwidth f D−pre less than one PRF. The value of constant factor ϕ depends on the Doppler bandwidth of signal in Equation (9). If ωPRF < f D < (ω + 1)PRF, ω = 1, 2, 3, • • • , then the constant factor ϕ will be chosen as ω.…”

Section: Analysis Of the Srcm Correction Function Mismatchmentioning

confidence: 99%

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Efficient Algorithm for SAR Refocusing of Ground Fast-Maneuvering Targets

et al. 2019

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The synthetic aperture radar (SAR) image of moving targets will defocus due to the unknown motion parameters. For fast-maneuvering targets, the range cell migration (RCM), Doppler frequency migration and Doppler ambiguity are complex problems. As a result, focusing of fast-maneuvering targets is difficult. In this work, an efficient SAR refocusing algorithm is proposed for fast-maneuvering targets. The proposed algorithm mainly contains three steps. Firstly, the RCM is corrected using sequence reversing, matrix complex multiplication and an improved second-order RCM correction function. Secondly, a 1D scaled Fourier transform is introduced to estimate the remaining chirp rate. Thirdly, a matched filter based on the estimated chirp rate is proposed to focus the maneuvering target in the range–azimuth time domain. The proposed method is computationally efficient because it can be implemented by the fast Fourier transform (FFT), inverse FFT and non-uniform FFT. A new deramp function is proposed to further address the serious problem of Doppler ambiguity. A spurious peak recognition procedure is proposed on the basis of the cross-term analysis. Simulated and real data processing results demonstrate the validity of the proposed target focusing algorithm and spurious peak recognition procedure.

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Section: Analysis Of the Srcm Correction Function Mismatchmentioning

confidence: 99%

“…Synthetic aperture radar (SAR) can image the scenes of interest during the day and night regardless of weather conditions, which attracts considerable attention worldwide [1][2][3][4][5][6][7][8][9][10]. SAR has been widely used in numerous remote sensing applications, such as marine observation, traffic monitoring and antiterrorism.…”

Section: Introductionmentioning

confidence: 99%

Efficient Algorithm for SAR Refocusing of Ground Fast-Maneuvering Targets

et al. 2019

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“…In this paper, a Chirp Z-transform (CZT) algorithm is introduced to replace the Fast Fourier Transform (FFT) used in traditional FMCW GPR. CZT is a spectrum calculation method based on spiral sampling, which can obtain high-precision spectra with low sampling points in the frequency band of interest [29,30]. In this investigation, a compact low-frequency narrow-band FMCW GPR for asphalt pavement thickness measurement is being built.…”

Section: Introductionmentioning

confidence: 99%

Improving FMCW GPR Precision through the CZT Algorithm for Pavement Thickness Measurements

Huang

Zhang

et al. 2022

Electronics

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Ground Penetrating Radar (GPR) application in road surface detection has been greatly developed in the past few decades, which enables rapid and economical estimation of pavement thickness and other physical properties in non-destructive testing (NDT) and non-contact testing (NCT). In recent years, with the rapid development of microwave and millimeter-wave solid-state devices and digital signal processors, the cost of Frequency-Modulated Continuous-Wave (FMCW) radar has dropped significantly, with smaller size and lighter weight. Thereafter, FMCW GPR is considered to be applied during pavement inspection. To improve the precision of FMCW GPR for NDT and NCT of pavement thickness, a Chirp Z-transform (CZT) algorithm is introduced to FMCW GPR and investigated in this paper. A FMCW + CZT GPR at 2.5 GHz with a bandwidth of 1 GHz was built, and laboratory and field experiments were carried out. The experimental results demonstrate that the FMCW + CZT GPR radar can obtain the sample thickness with low error and recognize subtle thickness variations. This method realizes the high precision thickness measurement of shallow asphalt pavement by FMCW radar with a narrow bandwidth pulse signal and would provide a promising low-cost measurement solution for GPR.

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“…Synthetic aperture radar (SAR) can image the observed scenes under all-time and allweather conditions, and it is receiving more and more attention all around the world [1][2][3][4][5][6]. It has been widely applied in modern remote sensing fields, for example, sea surface surveillance, ground traffic monitoring, and anti-terrorism.…”

Section: Introductionmentioning

confidence: 99%

Refocusing of Ground Moving Targets with Doppler Ambiguity Using Keystone Transform and Modified Second-Order Keystone Transform for Synthetic Aperture Radar

et al. 2021

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Ground moving targets will typically be defocused because of the range migration (RM) and Doppler frequency migration (DFM) caused by the unknown relative motions between the platform of synthetic aperture radar (SAR) and the ground moving targets. The received signal of the ground moving target easily exhibits the Doppler ambiguity, and the Doppler ambiguity leads to the refocusing difficulty of ground moving targets. To address these problems, a SAR refocusing method of ground moving targets with Doppler ambiguity based on modified second-order keystone transform (MSOKT) and keystone transform (KT) is presented in this paper. Firstly, the second-order phase is separated by the time reversing process. Secondly, MSOKT is performed to compensate the range curvature migration and DFM, and then the coefficient of the second-order phase is estimated. Finally, a well-refocused result of the moving target is achieved after KT and the estimated Doppler ambiguity number are used to eliminate residual range walk migration. The proposed method can accurately remove RM and DFM and effectively focus the moving targets without residual correction errors. Moreover, the effects of Doppler ambiguity (including Doppler center blur and spectrum split) and blind speed sidelobe are further avoided. On the basis of the analysis of cross-term for the multiple target case, the identification strategy of spurious peak of cross-term is proposed. Additionally, the developed method can be sped up by nonuniform fast Fourier transform without the interpolation operation. The effectiveness of the proposed method is verified by both airborne and spaceborne real data processing results.

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A Fast High-Resolution Imaging Algorithm for Helicopter-Borne Rotating Array SAR Based on 2-D Chirp-Z Transform

Cited by 7 publications

References 17 publications

Efficient Algorithm for SAR Refocusing of Ground Fast-Maneuvering Targets

Efficient Algorithm for SAR Refocusing of Ground Fast-Maneuvering Targets

Improving FMCW GPR Precision through the CZT Algorithm for Pavement Thickness Measurements

Refocusing of Ground Moving Targets with Doppler Ambiguity Using Keystone Transform and Modified Second-Order Keystone Transform for Synthetic Aperture Radar

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