• 한국자동차공학회논문집
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• 제18권4호
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• pp.54-61
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• 2010

In this paper, we design the signal processing unit to effectively support the proposed algorithm for an automotive Frequency Modulation Continuous Wave(FMCW) radar. In the proposed method, we can obtain the distance and velocity with improved error depending on each range(long, middle, and short) of the target. Since a high computational capacity is required to obtain more accurate distance and velocity for target in near range, the proposed signal processing unit employs the time de-interleaving and the frequency interpolation method to overcome the limitation. Moreover, for real-time signal processing, the parallel architecture is used to extract simultaneously the distance and velocity in each range.

• 대한원격탐사학회지
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• 제24권2호
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• pp.91-98
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• 2008

SAR에서 마이크로파의 진행방향으로의 속도성분을 가지고 움직이는 물체는 영상에서 azimuth 방향으로 이동된 위치에 상이 맺힌다는 현상은 이미 잘 알려져 있다. 대부분의 속도측정 알고리즘들은 실제 물체의 위치와 상이 맺힌 위치 사이의 거리를 측정함으로써 속도를 유추하였다. 그러나 움직이는 물체의 실제의 위치를 나타내는 지시자인 도로나 배의 물결모양은 일반적으로 SAR 영상에서의 식별도가 높지 않기 때문에 이러한 방법은 영상취득시의 조건이나 물체의 움직임 정도에 따라 적용이 제한적이다. 이에 본 연구에서는 SAR 원시자료 처리단계의 중간 산물인 range-compressed 영상의 azimuth 차분신호로부터 물체의 속도를 측정하는 새로운 방법을 제안한다. 이 방법은 움직이는 물체에 의한 도플러 중심주파수의 변이가 azimuth 차분신호에서의 위상변화를 일으킨다는 점에 기초한다. 일반적으로 SAR에서 감지하는 지표물의 위상은 SAR의 기하에 의하여 발생하는 도플러 변화율에 따라서 선형적으로 변한다. 이 선형변화위상과 몇 가지 상수 값을 갖는 위상들을 제거하고 남은 신호는 물체의 움직임과 직접적인 관련이 있으므로, 이로부터 속도를 구해낼 수 있다. 이 방법을 실제 ENVISAT ASAR영상을 이용하여 배의 속도를 구하는 데에 적용해 보았으며, 그 결과는 목표물의 위치에 따라 다른 양상을 보였다. 해상에 단독적으로 존재하는 배에 적용하였을 때는 0.1m/s 정도의 차이로 기존의 속도측정 알고리즘의 결과와 잘 일치하였으나, 육지에 인접한 연안의 배는 신호의 교란에 의해서 1m/s 이상의 오차를 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.158.5-158
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• 2001

Monopulse active homing radar requires velocity and angle information of target to track fast moving target. Target velocity can be estimated by measuring the frequency shift between transmitted and received frequencies. Angle information is obtained by measuring boresight error. Measurement of doppler frequency component in received signal is done through FFT analysis and interpolation algorithm for fine tuning. Boresight errors in azimuth and elevation axes are proportional to the power of each difference channel relative to sum channel. The target signal power in difference channel is estimated more precisely by measuring the power of FFT result cell of maximum ...

• 한국군사과학기술학회지
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• 제26권4호
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• pp.324-334
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• 2023

In this paper, the target simulator for RF signals was developed by using VST(Vector Signal Transceiver) and set by real-time signal processing SW programs. A function to process RF signals using FPGA(Field Programmable Gate Array) board was designed. The system functions capable of data processing, raw signals monitoring, target signals(simulated range, velocity) generating and RF environments data analyzing were implemented. And the characteristics of modulated signal were analyzed in RF environment. All function of programs for processing RF signal have options to store signal data and to manage the data. The validity of the signal simulation was confirmed through verification of simulated signal results.

• 전자공학회논문지
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• 제53권6호
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• pp.146-151
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• 2016

본 논문에서는 등속 직선 기동하는 수중표적의 CPA 상황에서의 방위각 정보를 이용하여 표적의 CPA 거리와 속도의 비를 추정하는 기법을 제시한다. 선행 연구를 통해 근접센서를 이용한 포락선 CPA 기법으로 이 값을 추정하는 방안이 제시되었으나, 이는 표적과 수신 센서의 거리가 가깝거나 다중경로로 인한 간섭효과가 커질 경우 성능이 떨어지는 문제를 가진다. 이에 이를 극복하는 방안으로 표적 방위각 정보를 이용하는 방위각 CPA 기법을 제시한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.5095-5111
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• 2016

The Probability Hypothesis Density (PHD) filter is a suboptimal approximation and tractable alternative to the multi-target Bayesian filter based on random finite sets. However, the PHD filter fails to track newborn targets when the target birth intensity is unknown prior to tracking. In this paper, a dual detection-guided newborn target intensity PHD algorithm is developed to solve the problem, where two schemes, namely, a newborn target intensity estimation scheme and improved measurement-driven scheme, are proposed. First, the newborn target intensity estimation scheme, consisting of the Dirichlet distribution with the negative exponent parameter and target velocity feature, is used to recursively estimate the target birth intensity. Then, an improved measurement-driven scheme is introduced to reduce the errors of the estimated number of targets and computational load. Simulation results demonstrate that the proposed algorithm can achieve good performance in terms of target states, target number and computational load when the newborn target intensity is not predefined in multi-target tracking systems.

• 제어로봇시스템학회논문지
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• 제20권1호
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• pp.48-57
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• 2014

It is suggested that the curvature trajectory be used to estimate the real-time moving sound sources and efficiently the robot estimating the sound sources. Since the target points of the real-time moving sound sources change, the mobile robot continuously estimates the changed target points. In such a case, the robot experiences a slip phenomenon due to the abnormal velocity and the changes of the navigating state. By selecting an appropriate curvature and navigating the robot gradually by using it, it is possible to enable the robot to reach the target points without having much trouble. In order to recognize the sound sources in real time, three microphones need to be organized in a straight form. Also, by applying the cross-correlation algorithm to the TDOA base, the signals can be analyzed. By using the analyzed data, the locations of the sound sources can be recognized. Based on such findings, the sound sources can be estimated. Even if the mobile robot is navigated by selecting the gradual curvature based on the changed target points, there could be errors caused by the inertia and the centrifugal force related to the velocity. As a result, it is possible to control the velocity of both wheels of the robot through the velocity PID controller in order to compensate for the slip phenomenon and minimize the estimated errors. In order to examine whether the suggested curvature trajectory is appropriate for estimating the sound sources, two mobile robots are arranged to carry out an actual experiment. The first robot is moved by discharging the sound sources, while the second robot recognizes and estimates the locations of the discharged sound sources in real time.

• 한국국방경영분석학회지
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• 제2권1호
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• pp.163-176
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• 1976

The artillery fire is characterized by great damage that can be inflicted simultaneously to an area through concentrated firing. The field artillery guns used in R.O.K. Army are generally old. Thus high values of their velocity errors cause wide dispersion of shell landings. Therefore effects of the concentrated firing is lessened. In this paper a general model which considers all error factors involved in firing in general, is established first. Then from this a basic model which includes the errors involved in concentrated firing only, such as the ballistic error, velocity error, target density function, and damage function, is extracted. Among many weapon systems now in use a specific one called gun 'A' is selected and its concentration effects are measured through computer simulation. The results show that as the velocity error of a battery increases, its target coverage capability, i. e. concentration effect, decreases. Therefore the need arises for the field artillery commander to know beforehand characteristics, i.e. velocity errors, of the guns in his unit and also to carefully examine the problem of battery arrangement with the gun characteristics in mind in order to maximize the damage effects of his artillery unit.

• 한국측량학회지
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• 제29권5호
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• pp.519-525
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• 2011

High-resolution earth-observing satellites acquire substantial amount of geospatial images. In addition to high image quality, high-resolution satellite images (HRSI) provide unprecedented direct georegistration accuracy, which have been enabled by accurate orbit determination technology. Direct georegistration is carried out by relating the determined position and attitude of camera to the ground target, i.e., projecting an image point to the earth ellipsoid using the collinearity equation. However, the apparent position of ground target is displaced due to the atmosphere and satellite velocity causing significant georegistration bias. In other words, optic ray from the earth surface to satellite cameras at 400~900km altitude refracts due to the thick atmosphere which is called atmospheric refraction. Velocity aberration is caused by high traveling speed of earth-observing satellites, approximately 7.7 km/s, relative to the earth surface. These effects should be compensated for accurate direct georegistration of HRSI. Therefore, this study presents the equation and the compensation procedure of atmospheric refraction and velocity aberration. Then, the effects are simulated at different image acquisition geometry to present how much bias is introduced. Finally, these effects are evaluated for Quickbird and WorldView-1 based on the physical sensor model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.268-273
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• 1991

Missile and target closing velocity is used in the proportional navigation(PN) missile guidance loop. But it is difficult to estimate the closing velocity when passive seeker is used and only the Line-of-Sight(LOS) rate is available in the guidance loop. In this study, new closing velocity estimation method is developed. This method uses LOS rate measurement only and uses some characteristics of PN guidance law. The Lyapunov method is used to analyze the stability of the developed estimation method.