• Title, Summary, Keyword: Imaging Radar

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Imaging of Concrete Specimens at Expanded Frequency Bandwidth Using Radar (레이더의 주파수 대역 합성에 따른 콘크리트 내부 탐사)

  • 이주희;임홍철
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.799-802
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    • 2001
  • For imaging of concrete specimens using radar, principles of radar and signal processing are discussed. Experimental data obtained from radar measurement of two different concrete specimens at two different frequency bandwidths of 2~3.4 GHz, 3.4~5.8 GHz and these two frequencies are combined to show better imaging. A signal processing scheme has been implemented to visualize the concrete specimens. Through combined frequency, imaging results of concrete specimens were improved.

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Bistatic ISAR Imaging with UWB Radar Employing Motion Compensation for Time-Frequency Transform (시간-주파수 변환에 요동보상을 적용한 UWB 레이다 바이스테틱 ISAR 이미징)

  • Jang, Moon-Kwang;Cho, Choon-Sik
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.7
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    • pp.656-665
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    • 2015
  • In this paper, we improved the clarity and quality of the radar imaging by applying motion compensation for time-frequency transform in B-ISAR imaging. The proposed motion compensation algorithm using UWB radar is verified. B-ISAR algorithm procedure and time-frequency transform for improved motion compensation are provided for theoretical ground. The image was created by a UWB Radar B-ISAR imaging algorithm method. Also, creating a B-ISAR imaging algorithm for motion compensation of time-frequency transformation method was used. The B-ISAR Imaging algorithm is implemented using STFT(Short-Time Fourier Transform), GWT(Gabor Wavelet Transform), and WVD(Wigner-Ville Distribution) approaches. The performance of STFT is compared with the GWT and WVD algorithms. It is found that the WVD image shows more clarity and decreased spread phenomenon than other methods.

Robust Transmission Waveform Design for Distributed Multiple-Radar Systems Based on Low Probability of Intercept

  • Shi, Chenguang;Wang, Fei;Sellathurai, Mathini;Zhou, Jianjiang;Zhang, Huan
    • ETRI Journal
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    • v.38 no.1
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    • pp.70-80
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    • 2016
  • This paper addresses the problem of robust waveform design for distributed multiple-radar systems (DMRSs) based on low probability of intercept (LPI), where signal-to-interference-plus-noise ratio (SINR) and mutual information (MI) are utilized as the metrics for target detection and information extraction, respectively. Recognizing that a precise characterization of a target spectrum is impossible to capture in practice, we consider that a target spectrum lies in an uncertainty class bounded by known upper and lower bounds. Based on this model, robust waveform design approaches for the DMRS are developed based on LPI-SINR and LPI-MI criteria, where the total transmitting energy is minimized for a given system performance. Numerical results show the effectiveness of the proposed approaches.

Probing of Concrete Specimens using Ground Penetration Radar

  • Rhim, HongChul
    • Corrosion Science and Technology
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    • v.3 no.6
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    • pp.262-264
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    • 2004
  • Ground Penetrating Radar (GPR) has been used to image inside concrete specimens embedded with steel bars and delamination. An imaging algorithm has been developed to improve measurement output generated from a commercial radar system. For the experiments, laboratory size concrete specimens are made with the dimensions of $1,000mm(W){\times}1,000mm(L){\times}250mm(D)$. The results have shown improved output of the radar measurements compared to commercially available processing methods.

High Resolution ISAR Imaging Based on Improved Smoothed L0 Norm Recovery Algorithm

  • Feng, Junjie;Zhang, Gong
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.12
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    • pp.5103-5115
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    • 2015
  • In radar imaging, a target is usually consisted of a few strong scatterers which are sparsely distributed. In this paper, an improved sparse signal recovery algorithm based on smoothed l0 (SL0) norm method is proposed to achieve high resolution ISAR imaging with limited pulse numbers. Firstly, one new smoothed function is proposed to approximate the l0 norm to measure the sparsity. Then a single loop step is used instead of two loop layers in SL0 method which increases the searching density of variable parameter to ensure the recovery accuracy without increasing computation amount, the cost function is undated in every loop for the next loop until the termination is satisfied. Finally, the new set of solution is projected into the feasible set. Simulation results show that the proposed algorithm is superior to the several popular methods both in terms of the reconstruction performance and computation time. Real data ISAR imaging obtained by the proposed algorithm is competitive to several other methods.

A Study on Block Processing Approach for Mono-Static Terrain Imaging Radar (모노스태틱 지형 영상 레이더의 블록 처리 기법 연구)

  • Ha, Jong-Soo;Cho, Byung-Lae;Lee, Jung-Soo;Park, Gyu-Churl;Sun, Sun-Gu;Kang, Tae-Ha
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.5
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    • pp.549-557
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    • 2013
  • This paper describes a block processing approach to detect targets in front of mono-static terrain imaging radar (TIR). It is difficult to employ several conventional imaging methods of the synthetic aperture radar(SAR) because the TIR is an ultra-wide-band(UWB) type of radar and employs a dechirp-on-receive process. To design an available imaging method, a block processing approach which conducts a range compression and an azimuth compression is proposed in this paper. The complete derivation of the proposed approach is presented. The results of simulations and field tests are demonstrated to show the performance and validity of the proposed approach.

Raw-data Processing Schemes in the Spotlight-mode SAR(Synthetic Aperture Radar) (Spotlight-mode SAR(Synthetic Aperture Radar)에서의 Raw-data Processing 기법 분석)

  • 박현복;최정희
    • Proceedings of the IEEK Conference
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    • pp.501-504
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    • 2000
  • The classical image reconstruction for stripmap SAR is the range-Doppler imaging. However, when the spotlight SAR system was envisioned, range-Bowler imaging fumed out to fail rapidly in this SAR imaging modality. What is referred to as polar format processing, which is based on the plane wave approximation, was introduced for imaging from spotlight SAR data. This paper has been studied for the raw data processing schemes in the spotlight-mode synthetic aperture radar. we apply the wavefront reconstruction scheme that does not utilize the approximation in spotlight-mode SAR imaging modelity, and compare the performance of target imaging with the polar format inversion scheme.

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A Novel 3-D Imaging Configuration Exploiting Synthetic Aperture Ladar

  • Guo, Liang;Huang, Yinli;Li, Xiaozhen;Zeng, Xiaodong;Tang, Yu;Xing, Mengdao
    • Current Optics and Photonics
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    • v.1 no.6
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    • pp.598-603
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    • 2017
  • Traditional three-dimensional (3-D) laser imaging systems are based on real aperture imaging technology, whose resolution decreases as the range increases. In this paper, we develop a novel 3-D imaging technique based on the synthetic aperture technology in which the imaging resolution is significantly improved and does not degrade with the increase of the range. We consider an imaging laser radar (ladar) system using the floodlight transmitting mode and multi-beam receiving mode. High 3-D imaging resolutions are achieved by matched filtering the linear frequency modulated (LFM) signals respectively in range, synthetic aperture along-track, and the real aperture across-track. In this paper, a novel 3-D imaging signal model is given first. Because of the motion during the transmission of a sweep, the Doppler shift induced by the continuous motion is taken into account. And then, a proper algorithm for the 3-D imaging geometry is given. Finally, simulation results validate the effectiveness of the proposed technique.

Radar Imaging of Concrete Specimens with Improved Resolution Using Expanded Frequency Bandwidth (주파수 대역 확장을 이용한 콘크리트 시편의 레이더 영상 분해능 향상)

  • 임홍철;이주희
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.1
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    • pp.13-21
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    • 2002
  • Frequency bandwidth has been combined to determine adequate frequency bandwidth which is necessary for nondestructive testing when using inverse synthetic aperture radar(ISAR). For imaging inside of concrete specimens using radar, the principles of radar and signal processing are discussed. Experimental data obtained from radar measurement of three different concrete specimens at two different frequency bandwidths of 2∼3.4 GHz, 3.4∼5.8 GHz and these two frequencies are combined to obtain improved imagery. A signal processing scheme has been implemented to visualize inside concrete specimens. The influence of frequency bandwidth was analyzed in nondestructive testing by changing frequency bandwidth for concrete specimen.

Signal subspace comparison between Physical & synthesized array data in echo imaging

  • Choi, Jeong-Hee
    • Proceedings of the KSRS Conference
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    • pp.262-267
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    • 1998
  • In Synthetic Aperture Radar(SAR) imaging, the echoed data are collected by moving radar's position with respect to the target area, and this operation actually gives effect of synthesizing aperture size, which in turn gives better cross range resolution of reconstructed target scene. Among several inversion scheme for SAR Imaging, we uses an inversion scheme which uses no approximation in wave propagation analysis, and try to verify whether the collected data with synthesized aperture actually gives the same support as that with physical aperture in the same size. To do this, we make a signal subspace comparison of two imaging models with physical and synthesized arrays, respectively. Theoretical comparison and numerical analysis using Gram-Schmidt procedures had been performed. The results showed that the synthesized array data fully span the physical array data with the same system geometry and strongly support the proposed inversion scheme valuable in high resolution radar imaging.

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