• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.459-469
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• 2017

An air-to-ground guidance missile aimed to hit a main battle tank(MBT) should detect a ground moving target and estimate the target position to guide. In this paper, we detect a front ground moving target by using FMCW(Frequency Modulated Continuous Wave) and estimate the position by forward-looking SAR(Synthetic Aperture Radar) via scanning certain front ground section by steering a beam with narrow beamwidth left to right mechanically. Also, by MLE(Maximum Likelihood Estimation), degree of how fast the target approach or recede from the radar can be figured out from the estimated radial velocity of the moving target. Subsequently, we generate a radar image via corrected matched filter from phase history including the radial velocity.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.2
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• pp.253-260
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• 2012

Target detection is very difficult with complex clutters in IRST(Infrared Search and Track) system for a long distance target. Especially sea-clutter and ocean-surface with non-uniform temperature distribution make it difficult to detect incoming targets in images obtained in sea environment. In this paper, we propose a novel method based on morphological method for estimation of ocean surface with non-uniform temperature flow. In order to estimate the exact ocean surface temperature flow, we divided it into upper and lower bound flow. And after estimating it, the final ocean surface temperature flow is derived by a mean value of the estimated results. Also, we apply the multi-weighted technique with a variety of sizes of structure elements to overcome sub-sampling effect by using morphology method. Experimental results for ocean surface images acquired from many different environments are compared with results of existing method to verify the performance of the proposed methods.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.218-227
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• 2017

In this paper, an algorithm to calculate both bearing and distance error for target detection and localization is proposed using the Cramer Rao lower bound to estimate the minium variance of their error in DOA (Direction Of Arrival) estimation. The performance of arrays in detection and localization depends on the accuracy of DOA, which is affected by a variation of SNR (Signal to Noise Ratio). The SNR is determined by sonar parameters such as a SL (Source Level), TL (Transmission Loss), NL (Noise Level), array shape and beam steering angle. For verification of the suggested method, a Monte Carlo simulation was performed to probabilistically calculate the bearing and distance error according to the SNR which varies with the relative position of the target in space and noise level.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.161-164
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• 1999

본 논문에서는 표적 추적 시스템에서 센서 어레이에 입사되는 표적신호에 대한 센서 출력 신호간의 지연시간 추정(TDE:Time Delay Estimation)을 위해 백색상호 상관법(CSP:Cross-Power Spectrum Phase Analysis)을 이용한다. 그러나 음파의 다중경로 전달특성 및 배경잡음의 영향으로 인해 CSP계수는 많은 클러터(Clutter)를 포함하게 되고 결국 방위 추정 오차의 요인이 된다. 따라서 센서 어레이 중심좌표를 기준으로 대칭 배열된 센서쌍(Pair)에 대한 CSP계수를 동기가산 하여 실제 표적 방향 이외의 방향정보를 제거하는 방법을 제안한다. 시간에 따라 각도를 변침하는 표적에 대한 표적기동분석 (BOTMA:Bearings Only Target Motion Analysis)을 위해 매 관측시간마다 동기가산을 행한 CSP결과를 누적하여 방위각 궤적을 형성하였을 때 시간 Window에 따라 약간의 차이는 있지만 약 10dB의 궤적 추적 성능을 확인하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.545-556
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• 2016

JPDAF is a method of updating target's state estimation by using posterior probability that measurements are originated from existing target in multi-target tracking. In this paper, we propose a multi-target tracking algorithm for falling cluster bombs separated from a mother bomb based on JPDAS method which is obtained by applying fixed-interval smoothing technique to JPDAF. The performance of JPDAF and JPDAS multi-target tracking algorithm is compared by observing the average of the difference between targets' state estimations obtained from 100 independent executions of two algorithms and targets' true states. Based on this, results of simulations for a radar tracking problem that show proposed JPDAS has better tracking performance than JPDAF is presented.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4
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• pp.65-69
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• 1996

In this paper, the techniques for target state analysis based on a single ping in the ocean environment are proposed and discussed. The first method utilizes the relationship between range and bearing in order to determine the aspect angle of target. The second method uses the Range-Doppler Map. The former method requires the multi-channel data, while the latter uses single channel data. It is concluded, from the simulation, that the target state analysis is quite possible and the techniques mentioned should be used simultaneously to get the improved results.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.83-91
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• 2001

This paper proposes the Focused beamforming to estimate the location of target residing near to the observation platform in the underwater environment. The Focused beamforming technique provides the location of target by the coherent summation of a series of incident spherical waveforms considering distinct propagation delay times at the sensor array. But due to the movement of the observation platform and the variation of the underwater environment, the shape of the sensor array is no longer to be linear but it becomes distorted as the platform moves. Thus the Focused beamforming should be peformed regarding to the geometric shape variation at each time. To estimate the target location, the artificial image plane comprised of cells is constructed, and the delays are calculated from each cell where the target could be proximity to sensors for the coherent summation. After the coherent combining, the beam pattern can be obtained through the Focused beamforming on the image plane. Futhermore to compensate the variation of the shape of the sensor array, the paper utilizes the Nth-order polynomial approximation to estimate the shape of the sensor array obeying the water pulley modeling. Simulation results show the performance of the Focused beamforming for different frequency bands of the radiated signal.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.87-93
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• 2017

A maximum likelihood (ML) approach is presented for estimating the mean of radar cross section (RCS) of a Swerling III target and its numerical solution methods are discussed. The solution methods are based on an approximate expression for implementing the expectation maximization (EM) algorithm. The methods are evaluated and compared through Monte Carlo simulations in terms of estimation accuracy and computational efficiency to obtain a most efficient method for both Swerling I and Swerling III targets. The methods are also compared with a previously reported method based on heuristics.

• Journal of IKEEE
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• v.22 no.3
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• pp.599-604
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• 2018

A Stepped Frequency Radar(SFR) is a method that realizes high resolution range estimation by increasing the frequency of transmission pulses at regular intervals to generate a wide synthetic bandwidth. However, in the case of a moving target, accurate range estimation becomes difficult due to the range-Doppler coupling. In this paper, the process of high resolution range estimation by compensation of the range-Doppler coupling with estimated velocity of the moving target using the SFR waveform with Coherent Pulse Train(CPT) is analyzed and it was verified through simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.1
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• pp.53-64
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• 2004

This paper proposes a monopulse beamforming network to estimate a target angle in interference conditions. The proposed system estimates the target direction of arrival (DOA) with two separate beamformings for azimuth and elevation with a planar may. The elevation is extracted from adaptive beamforming in the azimuth direction and the azimuth from adaptive beamforming in the elevation direction. Unlike conventional monopulse beamforming techniques using complex correction formulas or a cascaded architecture of an adaptive array and a mainlobe canceller, the proposed system is very efficient from the computational complexity. The advantage is from fact that the monopulse ratio of the proposed system does not depend on the adapted weights. Moreover, the proposed system can estimate the DOA of the target even for multiple mainlobe interferences since it does not need my kinds of mainlobe maintenance technique.