• Title/Summary/Keyword: 합성 개구 레이다

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Method of Analyzing the ISAR image of Electrically Large Objects Partially Coated with RAM Using PO Technique (PO 기법을 이용한 부분 코팅된 전기적 대형물체의 ISAR 해석 방법)

  • Noh, Yeong-Hoon;Kim, Woobin;Yook, Jong-Gwan;Hong, Ic-Pyo;Kim, Yoon-Jae;Oh, Wonseok
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.4
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    • pp.328-336
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    • 2020
  • This paper presents an asymptotic analysis method using the PO(physical optics) approximation technique to analyze the scattering contribution of an electrically large object partially coated with a radar absorbing material(RAM). By using the feature of the PO technique that can calculate the equivalent current value for each mesh independently, instead of analyzing the entire structure, scattering analysis was performed only by calculating the current on the area where the RAM coating is applied. By the numerical examples, the accuracy and the computation time of the proposed method were verified, and the computational efficiency of inverse synthetic aperture radar(ISAR) of the electrically large objects that require enormous resources is improved.

Efficient Fusion Method to Recognize Targets Flying in Formation (편대비행 표적식별을 위한 효과적인 ISAR 영상 합성 방법)

  • Kim, Min;Kang, Ki-Bong;Jung, Joo-Ho;Kim, Kyung-Tae;Park, Sang-Hong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.8
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    • pp.758-765
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    • 2016
  • This paper proposes a novel method for the recognition of the inverse synthetic aperture radar(ISAR) image of multiple targets flying in formation. Rather than separating the ISAR image of each target, the proposed method combines an ISAR image obtained by fusing the ISAR images in the training database. Fusion is conducted by optimizing the non-linear problem whose parameters are the aspect angle and the target location. Assuming that the aspect angle is properly estimated, the proposed method estimates the number of the targets and their locations by optimizing the template matching using PSO. In simulations using the F-16 scale model, the efficiency of the proposed method was demonstrated by yielding the ISAR image identical to that of targets in formation.

3-D Multiple-Input Multiple-Output Interferometric ISAR Imaging (3차원 Multiple-Input Multiple-Output 간섭계 ISAR 영상형성기법)

  • Kang, Byung-Soo;Bae, Ji-Hoon;Yang, Eun-Jung;Kim, Kyung-Tae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.6
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    • pp.564-571
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    • 2015
  • In this paper, we propose a multiple-input, multiple-output(MIMO) interferometric radar network system to generate three-dimensional (3-D) MIMO interferometric inverse synthetic aperture radar(InISAR) image. In the MIMO interferometric radar network system, the MIMO InISAR image can be formed by an incoherent summation of multiple bistatic InISAR images that show 3-D scatterers of a target observed at different bistatic interfermetric configurations, respectively. Because bistatic-sccattering physics of a target at different viewpoints are visible in the 3-D MIMO InISAR image, it can provide various scatterering physics properties of a target, and can be used for target classification as a useful feature vector. Simulations validate that our proposed method successfully finds locations of scatterers of a target in MIMO radar interferometric network system.

A study on Modeling Method to Extract some Information for Scatterer Points of a Target (표적 산란점 정보 추출을 위한 모델링 기법 연구)

  • Nam, Dukjin;Hwang, Inseong
    • Journal of the Korea Society for Simulation
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    • v.30 no.4
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    • pp.21-29
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    • 2021
  • Inverse synthetic aperture radar (ISAR) image is a powerful tool to show the major scattering regions (scatterer points) on the target. It is normally used to identify and classify targets. Finding information for the scatter points of ISAR image plays an important role in modeling the features of targets. In this paper, we propose a modeling method to extract some information about the scatterer points by minimizing approximating error. Here, the extracted information include not only the location of scatterer points but also some statistical data about the error of the their location. These extracted data can be used to implement the randomness of the location of the scatterer points. Furthermore, we reconstruct an image from the extracted data for scatterer points obtained by our proposed method. And we show that the reconstructed ISAR image is well approximated to the original ISAR image in order to justify our proposed modeling method.

A Complex Valued ResNet Network Based Object Detection Algorithm in SAR Images (복소수 ResNet 네트워크 기반의 SAR 영상 물체 인식 알고리즘)

  • Hwang, Insu
    • Journal of the Korea Institute of Military Science and Technology
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    • v.24 no.4
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    • pp.392-400
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    • 2021
  • Unlike optical equipment, SAR(Synthetic Aperture Radar) has the advantage of obtaining images in all weather, and object detection in SAR images is an important issue. Generally, deep learning-based object detection was mainly performed in real-valued network using only amplitude of SAR image. Since the SAR image is complex data consist of amplitude and phase data, a complex-valued network is required. In this paper, a complex-valued ResNet network is proposed. SAR image object detection was performed by combining the ROI transformer detector specialized for aerial image detection and the proposed complex-valued ResNet. It was confirmed that higher accuracy was obtained in complex-valued network than in existing real-valued network.

Optimization Design of Non-Integer Decimation Filter for Compressing Satellite Synthetic Aperture Radar On-board Data (위성 탑재 영상레이다의 온보드 데이터 압축을 위한 비정수배 데시메이션 필터 최적화 설계 기법)

  • Kang, Tae-Woong;Lee, Hyon-Ik;Lee, Young-Bok
    • Journal of the Korea Institute of Military Science and Technology
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    • v.24 no.5
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    • pp.475-481
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    • 2021
  • The on-board processor of satellite Synthetic Aperture Radar(SAR) digitizes the back-scattered echoes and transmits them to the ground. As satellite SAR image of various operating conditions including broadband and high resolution is required, an enormous amount of SAR data is generated. Decimation filter is used for data compression to improve the transmission efficiency of these data. Decimation filter is implemented with the FIR(Finite Impulse Response) filter and here, the decimation ratio and tap length are constrained by resource requirements of FPGA used for implementation. This paper suggests to use a non-integer ratio decimation filter in order to optimize the data transmission efficiency. Also, it proposes a filter design method that remarkably reduces the resource constraints of the FPGA in-use via applying a polyphase filter structure. The required resources for implementing the proposed filter is analysed in this paper.

A Study on Transmission Signal Design Using DAC to Reduce IQ Imbalance of Satellite-Mounted Synthetic Aperture Radar Transmitter (위성 탑재 영상레이다 송신기의 IQ 불균형 저감을 위한 DAC를 이용한 송신 신호 설계 기법에 관한 연구)

  • Lee, Young-Bok;Kang, Tae-Woong;Lee, Hyon-Ik
    • Journal of the Korea Institute of Military Science and Technology
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    • v.25 no.2
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    • pp.144-150
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    • 2022
  • The on-board processor of satellite synthetic aperture radar(SAR) generates transmission signal by digital signal processing, converts it into an analog signal. At this time, the transmission signal generated from the baseband requires the frequency modulation to convert it to the high-frequency band in order to improve the stability. General frequency modulation method using local oscillator(LO) causes IQ imbalance due to phase error/magnitude error and these error reduce performance of SAR. To generate transmission signal without phase/magnitude error, this paper suggests design method of the frequency modulation method using digital to analog converter(DAC) at on-board SAR. For design, this paper analyzes the characteristic of DAC mode and uses pre-compensation filter. To analyze the proposed method performance, performance index are compared with IQ imbalance signals. This method is suitable for on-board SAR using fast sampling DAC and has the advantage of being able to solve IQ imbalances.

A Design Method for Pre-Distortion Compensation of SAR Chirp Signal based on Envelop Sampling and Interpolation Filter (위성 탑재 영상레이다 첩 신호의 전치왜곡 보상을 위한 포락선 샘플링 및 보간 필터 기반의 설계 기법)

  • Lee, Young-Bok
    • Journal of the Korea Institute of Military Science and Technology
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    • v.25 no.4
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    • pp.347-354
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    • 2022
  • The synthetic aperture radar(SAR) is an equipment that can acquire images in all weathers day and night based on radar signals. The on-board processor of satellite SAR generates transmission signal by digital signal processing, converts it into an analog signal and transmits to antenna. Until the transmission signal generated by on-board processor is output, the signal passes the transmission cables and analog devices. At this time, these hardware distort the signal and makes SAR performance worse. To improve the performance, pre-distortion technique is used. But, general pre-distortion using taylor series is not sufficient to compensate for the distortion. This paper suggests transmit signal design method with improved pre-distortion. This paper uses envelop sampling method and interpolation filter for frequency domain compensation. The proposed method accurately compensates the hardware distortion and reduces resource usage of FPGA. To analyze proposed method's performance, IRF characteristics are compared when the proposed method applies to signal with errors.

Imaging Method for Array Structured Bistatic Ground-to-Air Radar (배열 구조 바이스태틱 지대공 레이다의 이미징 기법)

  • Choi, Sang-Hyun;Yang, Dong-Hyeuk;Song, Ji-Min;Yang, Hoon-Gee
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.8
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    • pp.599-607
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    • 2018
  • This paper presents a ground-to-air bistatic radar system and its implementation algorithm, which resembles an SAR(synthetic aperture radar) reconstruction algorithm. Via cooperative working between a standoff transmitting radar and an array of ground based receiving radars, it detects and images moving targets under clutter in the air. In the proposed system, the whole receiving antenna aperture is synthesized by physical ground based radars, and thus, unlike conventional SAR, it does not require long illumination time of the target area. The reconstruction algorithm uses planewave approximation based polar format processing, which alleviates the requirement of positioning the receiving radars, which can cause grating lobes if not chosen properly. We derive a reconstruction algorithm including clutter suppression and discuss implementation issues, such as the resolution of a reconstructed image and the method of compensation for the irregularity of the receiving radars' positions. A simulation that validates the proposed algorithm is also shown.

Bistatic Synthetic Aperture Radar Imaging Using a Monostatic Equivalent Model (모노스태틱 등가 모델을 활용한 바이스태틱 SAR 영상 형성에 관한 연구)

  • Ryu, Bo-Hyun;Kang, Byung-Soo;Lee, Myung-Jun;Kim, Kyung-Tae
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.9
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    • pp.693-700
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    • 2018
  • In this paper, we propose a method to generate SAR(synthetic aperture radar) images for bistatic radar. The bistatic SAR can overcome several limitations of monostatic SAR, because the former can be applied to a variety of scenarios, compared to the latter. However, no study has been conducted on bistatic SAR imaging so far. In this paper, we propose a method to generate bistatic SAR images using the monostatic equivalent model and conventional monostatic SAR imaging algorithms. Simulations using airborne SAR in the bistatic geometry validated the efficacy of the proposed method.