• Title/Summary/Keyword: Direction ambiguity

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The Direction Finding Ambiguity Analysis for 3 Element and 4 Element Phase Interferometer DF System (3소자 및 4소자 위상인터페로미터 방탐시스템의 방탐모호성분석)

  • Lee, Jung-Hoon;Woo, Jong-Myung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.4
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    • pp.544-550
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    • 2014
  • In this paper, we have proposed a novel method which can analysis the direction finding ambiguity analysis for array geometry in 3 channel and 4 channel multiple baseline direction finding system. Generally, the direction finding ambiguity in the 3 element and 4 element phase interferometer direction finding system is calculated by the simulation for the array spacing or by the probability with the selected antenna array spacing. There are some restrictions to obtain the ambiguity of direction finding system in these methods. The former performs a simulation with every antenna array spacing and the latter calculates the ambiguity with the selected antenna array spacing. To overcome those restrictions, This paper proposed the novel method to calculate the ambiguity using the imaginary antenna array spacing and the phase difference prior to the modular operation in direction finder. Using the proposed method, we obtain the ambiguity probability for each of array geometry composed of multiple baseline. After performing the simulation with the selected antenna array spacing to verify the proposed method, we compared the calculated result data with the simulation data.

A Design of Simple and Precision Direction Finder with a Combination of an Amplitude Measurement and Phase Measurement

  • Lim Joong-Soo
    • International Journal of Contents
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    • v.1 no.2
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    • pp.35-38
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    • 2005
  • This paper describes a design of simple and precision direction finder that can be adapted to shipboard or mobile vehicles used for Electronic support measure, ELINT and radio signal monitoring systems. The direction finding technology has improved with monolithic integrated circuit, linear array antennas, and interferometer. Interferometer uses the phase-comparison principle and has a good direction finding accuracy but it has an ambiguity problem. We suggest a simple ambiguity solver using phase-comparison technology with amplitude-comparison principle. The direction finding device that has been designed by the suggested method has 0.7 degree RMS error in azimuth angle and 0.6 degree RMS error in elevation angle in 0.5 - 2.0 GHz.

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Direction Finding Method of the Uniform Circular Array Antenna Using the Pattern of Phase Differences (원형배열 안테나의 위상차 패턴을 이용한 방향탐지 기법)

  • Lim, Joong-Soo
    • Journal of the Korea Convergence Society
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    • v.10 no.1
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    • pp.1-6
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    • 2019
  • In this paper, we have studied a direction finding method of the radio signal by comparing the phase difference and its pattern from the uniform circular array antenna. In the phase comparison direction finding, if the length of the antenna baseline is longer than 0.5 wavelength of the incident signal, azimuth ambiguity occurs in which two or more azimuth angles are calculated in the same phase difference. The azimuthal ambiguity is removed by fusing the phase difference of the 5 antennas. The developed ambiguity elimination technology reduces the azimuth error where the antenna baseline is shorter than 1.236 wavelength in the uniform circular array with five antennas. This algorithm is very useful for the design of direction finder of an electronic information system.

Direction Finding and Tracking using Single-Ring Circular Array Antenna and Space Division Table (단원형배열안테나와 공간분할테이블을 이용한 방향탐지 및 추적)

  • Park, Hyeongyu;Woo, Daewoong;Kim, Jaesik;Park, Jinsung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.25 no.2
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    • pp.117-124
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    • 2022
  • Single-ring circular array antennas can be applied to direction finding systems in order to use nose-section in other purposes, and the interferometry is a proper direction finding method to those systems. We usually make the interferometer baseline long enough to achieve good angular accuracy. However, an interferometer with baseline longer than a half-wavelength has the ambiguity problem. In this paper, we present a novel method for solving the ambiguity problem in interferometry systems. This technique is based on the amplitude comparison method and the space division table, and it can place a target within the angular region in which the ambiguity problem does not occur by roughly estimating direction-of-arrival. The Monte Carlo simulation results show that proposed method can effectively remove the ambiguity problem in the system.

Signal Processing for Improvement of Resolution and Direction Ambiguity of Source in Line Array (선 배열에서 표적체의 방위 모호성과 분해능 향상을 위한 신호처리 기법)

  • 손윤준;천승용;김기만
    • The Journal of the Acoustical Society of Korea
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    • v.22 no.6
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    • pp.482-488
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    • 2003
  • Line may receiver contains an ambiguity on conjugate bearings, because of lacking aperture in transverse direction. To solve the left/right bearing ambiguity of line-array receiver we used line-array with cardioid beam. In addition, the synthetic aperture method adopts coherent processing of sub-aperture signals at successive time intervals in the beam domain. We presented performances about division of left/right bearing ambiguity according to array synthetic number of times in this paper.

Influence of Goal Ambiguity in Institutional Evaluation of Government-funded Research Institutes (정부출연연구기관의 기관평가에서 목표 모호성의 영향에 관한 연구)

  • Koo, Hoonyoung
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.43 no.4
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    • pp.84-92
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    • 2020
  • In order to analyze the organizational performance of government-funded research institutes, four independent variables (organization size, organization age, evaluation system, organization location) and goal ambiguity were empirically analyzed. Although there are existing studies on institutional evaluation, which is the organizational performance of government-funded research institutes, there are differences in research in that it is an empirical analysis analyzed from the perspective of goal ambiguity and that the evaluation system, which is the specificity of institutional evaluation, is included in the analysis. As a result of the analysis, organizational location was the only independent variable that had a direct significant effect on organizational performance, and goal ambiguity showed a significant mediating effect for all independent variables. This indicates that goal ambiguity plays an important role in the organizational performance of government-funded research institutes, and to reduce this, increase the size of the organization, pay attention to establishment of the organization for organizational age, and that it is desirable to have an independent research group in the government department for the organization location. In addition, it was supported that the improvement effect of the evaluation system is proceeding in a desirable direction in terms of goal ambiguity.

Direction of Arrival Estimation of GNSS Signal using Dual Antenna

  • Ong, Junho;So, Hyoungmin
    • Journal of Positioning, Navigation, and Timing
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    • v.9 no.3
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    • pp.215-220
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    • 2020
  • This paper deal with estimating the direction of arrival (DOA) of GNSS signal using two antennae for spoofing detection. A technique for estimating the azimuth angle of a received signal by applying the interferometer method to the GPS carrier signal is proposed. The experiment assumes two antennas placed on the earth's surface and estimates the azimuth angle when only GPS signal are received without spoofing signal. The proposed method confirmed the availability through GPS satellite placement simulation and experiments using a dual antenna GPS receiver. In this case of using dual antenna, an azimuth angle ambiguity of the received signal occurs with respect to the baseline between two antennas. For this reason, the accurate azimuth angle estimation is limits, but it can be used for deception by cross-validating the ambiguity.

Performance Comparison to Solve Angle Ambiguity Needed to Angle of Arrival Estimation in 2D Radar Interferometer (2차원 레이다 간섭계에서 각도 추정 알고리즘의 각도 모호성 해소 성능 비교)

  • Cho, Byung-Lae;Lee, Jung-Soo;Lee, Jong-Min;Sun, Sun-Gu
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.3
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    • pp.410-413
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    • 2012
  • This study describes the performance comparison to solve angle ambiguity needed to angle of arrival estimation in 2D radiometer. There are three algorithms to solve its ambiguity such as phase-comparison monopulse method, digital beam-forming method and least square error of the phase difference in 2D radar interferometer. To estimate two direction angles, phase-comparison monopulse method is sequentially applied to azimuth and elevation direction. To analyze the performance of these methods, probability of solving angle ambiguity and execution time have been chosen as performance indexes. Through the Monte Carlo simulation, we have verified that phase-comparison monopulse method is most effective in real-time signal processing application.

A Technology of Microwave Direction Finding with Circular Array Combination Method (원형 배열 복합 방식을 이용한 초고주파 방향 탐지 기술)

  • Lim Joong-Soo;Jung Chul-Gu;Chae Gyoo-Soo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.6 s.97
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    • pp.549-555
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    • 2005
  • This paper describes a microwave direction finding technology which is used for RF signal acquisition and monitoring systems. This paper suggests a direction finding method which use a combination of the amplitude-comparison technology and the phase-comparison technology. The amplitude-comparison technology uses the amplitude difference of the RF signals received from the array antennas of direction finding system and removes the ambiguity of wave incident bearing. The phase-comparison technology uses the phase difference of the RF signals received from the same nay antennas and makes a good direction finding accuracy. The suggested direction finding technology is designed to place 8 array antennas in a $45^{\circ}$ distance around the circle for $360^{\circ}$ azimuth angle. Also it is designed to use the phase difference of the received signals ken two nearby antennas to measure the signal incident direction accurately and to use the amplitude difference to remove the ambiguity of wave incident bearing. The simulation and measurement results are under $0.5^{\circ}$ bearing error in $2.0\~6.0$ GHz when SNR is 30 dB.

Comparison of Korean & Chinese about Cognitive Approach to 'N+shang' through 'loushang' ('누상(樓上)'을 통해보는 'N+상(上)'에 대한 한국인과 중국인의 인지적 접근 비교)

  • Park, Minsoo
    • Cross-Cultural Studies
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    • v.39
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    • pp.177-190
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    • 2015
  • This study investigates the difference of the cognitive approach of Korean and Chines of the space direction that modern Chinese space phrase 'N+shang'. For this, we defined the spatial meaning of the noun 'N' and space noun 'shang' then investigate the conditions when 'N+shang' means 'the substance interior direction' and 'the substance exterior direction'. Also via 'lou+shang', we conducted the survey to Korean and Chinese students in order to see the what kind of cognitive differences be shown when they approach and translate the space direction of 'N+shang' structure. As a result of the survey, we were able to find cultural difference of spatial approach of 'N+shang' between these two countries, Korean select the cognitive inference path; from the substance external direction to internal direction while Chinese select from internal to external.