• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.6
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• pp.543-551
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• 2020

In this paper, we introduce a method to improve the accuracy of the length estimation of targets using a radar. The HRRP (High Resolution Range Profile) obtained from a received radar signal represents the one-dimensional scattering characteristics of a target, and peaks of the HRRP means the scattering centers that strongly scatter electromagnetic waves. By using the extracted scattering centers, the downrange length of the target, which is the length in the RLOS (Radar Line of Sight), can be estimated, and the real length of the target should be estimated considering the angle between the target and the RLOS. In order to improve the accuracy of the length estimation, parametric estimation methods, which extract scattering centers more exactly than the method using the HRRP, can be used. The parametric estimation method is applied after the number of scattering centers is determined, and is thus greatly affected by the accuracy of the number of scattering centers. In this paper, in order to improve the accuracy of target length estimation, the number of scattering centers is estimated by using AIC (Akaike Information Criteria), MDL (Minimum Descriptive Length), and GLE (Gerschgorin Likelihood Estimators), which are the source number estimation methods based on information theoretic criteria. Using the ESPRIT algorithm as a parameter estimation method, a length estimation simulation was performed for simple target CAD models, and the GLE method represented excellent performance in estimating the number of scattering centers and estimating the target length.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.316-323
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• 2002

In this paper, we propose a counter-countermeasure (CCM) in a crossed array tracker for efficient target tracking under countermeasures (CM) operated by a target. The proposed CCM adepts two detection bands and uses the signal distribution characteristics to discriminate between the target and the CMs. To avoid wrong detection of a target position due to missing signal pulses, it predicts current target position based on previous target position. To evaluate the performance of the proposed CCM in a crossed array tracker, we perform numerical simulations for target signal extraction and target tracking under various conditions. The simulation results show that the proposed CCM removes the CM effect well and tracks the target efficiently.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.6
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• pp.60-69
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• 2000

In this paper we propose a new two-color signal processing algorithm for efficient target tracking under complicated condition including interfernces such as background noises and countermeasures. For the efficient target tracking, we adopt two detection bands, and define the ratio between two band signals which represents the spectral distribution characteristics of a target or interference. The proposed algorithm detects the ratio of interference, and extracts only the target signal from the target and the interference mixed signal by using it. To evaluate the performance of the proposed algorithm, we apply it to a rosette tracker and perform various simulations. The simulation results show that the proposed algorithm extracts the target signal from the mixed signal well. The proposed algorithm is also ready to be applied to a real system since it is simple and adaptive for environment change.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.6
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• pp.493-497
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• 2016

Infrared (IR) imaging is capable of detecting targets that are not visible at night, thus it has been widely used for the security and defense system. However, the quality of the IR image is often degraded by low resolution and noise corruption. This paper addresses target segmentation with the IR image. Multiple regions of interest (ROI) are extracted by the multi-level segmentation and targets are segmented from the individual ROI. Each level of the multi-level segmentation is composed of a k-means clustering algorithm an expectation-maximization (EM) algorithm, and a decision process. The k-means clustering algorithm initializes the parameters of the Gaussian mixture model (GMM) and the EM algorithm iteratively estimates those parameters. Each pixel is assigned to one of clusters during the decision. This paper proposes the selection and the merging of the extracted ROIs. ROI regions are selectively merged in order to include the overlapped ROI windows. In the experiments, the proposed method is tested on an IR image capturing two pedestrians at night. The performance is compared with conventional methods showing that the proposed method outperforms others.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.1
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• pp.100-110
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• 1994

레이다 신호는 대표적인 전자파 신호로서 주변환경에 따라 시간, 주파수, 공간 영역에서 고유한 신호특성을 가지고 있으며, 신호처리 기법도 다양하다. 본 논문에서는 먼저 레이다를 위한 전파 신호처리 의정의와 필요성을 언급한뒤, 레이다 신호환경 특성을 살펴보고 신호처리를 위한 신호의 시간 및 스펙트럼 특성에 대해 기술하였다. 그리고, 신호특성에 적합한 신호처리기의 구현을 위해 레이다 신호처리에 관 련된 주요 기법에 대해 개괄적으로 설명하였다. 레이다 신호처리 분야는 일반적으로 잘 알려진 음성이 나 영상신호처리 분야와 달리 고유한 알고리듬과 구조가 요구된다. 신호처리기법으로서 레이다 파형설 계, 해상도 모호성, 펄스압축, 클러터제거, 도플러처리, 일정오경보탐지, 클러터 지도, 표적군 형성/ 추출, 표적식별, 레이다영상기법, 적응배열처리 등에 관해 개괄적으로 설명하였다. 레이다 선호처리 기술은 "스마트"한 레이다를 위한 두뇌 역할을 하기때문에 그 필요성과 중요성이 증가하고 있다. 그러나, 고속, 대용량의 신호를 주어진 빔 주사시간동안에 실시간으로 처리하여 표적 정보를 추출해야 하기 때문에 아직도 상용 프로세서의 속도 한계내에서 알고리듬의 수행에 다소 제약을 받고 있으나, 최근 디지탈 신호처리 전용의 고속 칩의 출현으로 많은 발전을 가져오고 있다. 끝으로, 향후 레이다 신호처리 발전 추세와 응용분야에 대해 살펴보았다. 응용분야는 군수 및 민수용의 겸용 파급효과가 매우 크고, 군용의 대공탐색 및 조기경보, 전장감시뿐만 아니라 전투기 탑재용으로 필수적이며, 특히 민수용의 공 항, 항공기, 선박, 위성 등 매우 다양하다. 최근 발전추세에 따른 기술로서 다중모드 신호처리, 고집적 회로기술, 적응배열, 디지탈 빔형성, 적응성, 고분해능 및 방향성, 표적식별, 다차원 신호처리에 대해 언급 하였다.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.84-90
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• 2000

The bearing detection of radiated target noise is very important at underwater acoustic measurement and passive detection. It differs the arrival tines of received signal at each sensor. Therefore, the bearing can be obtained from the time delay. This paper proposes a new algorithm using the RLSL adaptive filter for TDE. The proposed method is particularly attractive when there is a limitation of priori information about the received signal spectra and when the delay is subject to variation. As the simulation results, it is shown that the proposed algorithm has better convergence characteristics and TDE speed, and so that the usefulness of proposed algorithm is confirmed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1090-1097
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• 2007

The multibeam surveillance radar is a state-of art of 3D radar technology. It applies the stacked beam-on-received realized by a digital beamformer. In this paper, a design concept of beamformer and a method of target altitude extraction for multibeam surveillance radar in the normal environmental condition considering no multipath situations are proposed and investigated. The extraction algorithm based on antenna sine space coordinated system in a FFT digital beamformer is described. The proposed algorithm is simulated by 1 look-up table data and confirmed to have consistent results in accordance with a variety of target altitudes and a full radar frequency range.

• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.549-558
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• 2020

In this paper, the method is discussed such that the robustness of automatic initiated narrowband target tracking is improved in passive sonar. In the case of automatic tracking initiation as target in passive sonar, due to a number of clutter, the clutter is initiated as target and tracked which prohibits the operation capability. The associated probability and information entropy of measurements, extracted from detection data, is calculated to keep going on automatic target initiation and tracking of true target, but reduce the automatic initiation and tracking of clutter. If the association probability and information entropy of the extracted measurements is satisfied for the predefined conditions, the procedure of automatic initiation begins. Using sea-trial data, simulations are executed and the results from the proposed method indicate that it keeps the automatic target initiation and tracking of true target and suppresses the automatic target initiation and tracking of clutters in contrary to the conventional method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.299-309
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• 2013

A comprehensive SAR(Synthetic Aperture Radar) simulation is considered to be a complicated task since a full knowledge of the signal propagation characteristics, antenna pattern, system internal errors and interference noises should be taken into account. In high resolution target application modes, the time varying nature of target RCS(Radar Cross Section) strongly affects the generated SAR images. In this paper, in-depth SAR simulations are performed and analyzed incorporating the STK tools and MATLAB software. STK provides realistic orbit parameters while its radar module helps to extract accurate radiometric parameters of ground targets. SAR raw data corresponding to a given target is generated and processed using MATLAB simulator. The performance is measured by PSLR(Peak Sidelobe Ratio) and ISLR(Integrated Sidelobe Ratio) for a point target, which can be used as reference parameters for accurate radiometric calibration. Finally, high resolution target simulations are performed by adopting time varying target RCS characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.10
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• pp.981-989
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• 2011

In this paper, we performed radar target classification for the five scale models using ultra-wideband measured signal. In order to compare the performance, the 2 GHz(2~4 GHz), 4 GHz(2~6 GHz), and 6 GHz(2~8 GHz) bandwidth were used. Short time Fourier transform(STFT) and continuous wavelet transform(CWT) are used for target feature extraction. Extracted feature vectors are used as input for the multi-layerd perceptron(MLP) neural network classifier. The results show that as the bandwidth is wider, the performance is better.