• Title/Summary/Keyword: Multi-path effect

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An Analysis on the Degradation of Elevation Angle Accuracy Due to the Multi-Path Effect Using a Phased Array Antenna and the Beam Pattern Optimization to Minimize Its Degradation (위상배열 안테나를 활용한 다중 경로 효과에 의한 고각 정확도 열화 분석 및 열화 최소화를 위한 빔 패턴 최적화)

  • Kim, Young-Wan;Lee, JaeMin;Chae, Heeduck;Jin, Hyung-suk;Park, Jongkuk
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.12
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    • pp.1036-1043
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    • 2016
  • In this paper, an analysis about the elevation angle accuracy degradation of an APAR(Airport Precision Approach Radar) due to the multi-path effect using a phased array antenna was performed. An APAR installed around a runway of airport will be continuously affected in a runway surface of the fixed environment. In this paper, an analysis about the elevation angle accuracy degradation of APAR due to the multi-path effect of runway surface was conducted through a calculation of monopluse slope and sum/difference beam pattern analysis of array antenna. Also, a difference pattern for monopulse to minimize this degradation was optimized in an appropriate configuration to improve a elevation angle accuracy. Finally, a degree of improvement of elevation angle accuracy was confirmed by calculating a monopulse slope including the ground reflection after applying optimized difference patterns of array antenna.

Two-dimensional Localization of Array Elements Placed on a Sea Floor Using M-sequence Signal in Multipath Ocean Environment (M-계열 송신 신호를 이용한 다중 경로 해양 환경에서의 해저면 설치 선배열 센서의 2차원 위치 추정)

  • 오택환;나정열;석동우
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.8
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    • pp.686-694
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    • 2002
  • This paper proposes an algorithm for estimating positions of array elements placed on a sea floor using acoustic signal in multipath ocean environment. The positions of array elements are estimated by using the travel times of m-sequence signal influenced by the multi-paths environment. The horizontal distance between source and receiver calculated based on the ray model. The proposed paper the algorithm is verified by both simulation data and field experiment in the Bast Sea.

A development of map building sensor system for mobile robot using low cost photo sensor

  • Hyun, Woong-Keun
    • Journal of information and communication convergence engineering
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    • v.7 no.3
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    • pp.281-285
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    • 2009
  • Mobile robot has various sensors for describing the external world. The ultrasonic sensor widely applied to the most mobile robot to detect the obstacle and environment owing to low cost, its easy to use. However, ultrasonic sensor has major problems: the uncertainty information of sensor, false readings caused by specular reflection, multi path effect, low angular resolution and sensitivity to changes in temperature and humidity. This paper describes a sensor system for map building of mobile robot. It was made of low cost PSD (Position Sensitive Detector) sensor array and high speed RISC MPU. PSD sensor is cost effective and light weighting but its output signal has many noises. We propose heuristic S/W filter to effectively remove these noises. The developed map building sensor system was equipped on a mobile robot and was compared with ultrasonic sensor through field test.

EKF based Mobile Robot Indoor Localization using Pattern Matching (패턴 매칭을 이용한 EKF 기반 이동 로봇 실내 위치 추정)

  • Kim, Seok-Young;Lee, Ji-Hong
    • The Journal of Korea Robotics Society
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    • v.7 no.1
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    • pp.45-56
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    • 2012
  • This paper proposes how to improve the performance of CSS-based indoor localization system. CSS based localization utilizes signal flight time between anchors and tag to estimate distance. From the distances, the 3-dimensional position is calculated through trilateration. However the error in distance caused from multi-path effect transfers to the position error especially in indoor environment. This paper handles a problem of reducing error in raw distance information. And, we propose the new localization method by pattern matching instead of the conventional localization method based on trilateration that is affected heavily on multi-path error. The pattern matching method estimates the position by using the fact that the measured data of near positions possesses a high similarity. In order to gain better performance of localization, we use EKF(Extended Kalman Filter) to fuse the result of CSS based localization and robot model.

Sonar Map Construction for Autonomous Mobile Robots Using Data Association Filter (데이터 연관 필터를 이용한 자율이동로봇의 초음파지도 작성)

  • Lee Yu-Chul;Lim Jong-Hwan;Cho Dong-Woo
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.9
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    • pp.539-546
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    • 2005
  • This paper describes a method of building the probability grid map for an autonomous mobile robot using the ultrasonic DAF(data association filter). The DAF, which evaluates the association of each data with the rest and removes the data affected by the specular reflection effect, can improve the reliability of the data for the Probability grid map. This method is based on the evaluation of possibility that the acquired data are all from the same object. Namely, the data from specular reflection have very few possibilities of detecting the same object, so that they are excluded from the data cluster during the process of the DAF. Therefore, the uncertain data corrupted by the specular reflection and/or multi-path effect, are not used to update the probability map, and hence building a good quality of a grid map is possible even in a specular environment. In order to verify the effectiveness of the DAF, it was applied to the Bayesian model and the orientation probability model which are the typical ones of a grid map. We demonstrate the experimental results using a real mobile robot in the real world.

A Study on the RF performance analysis for Multi-band Ultra Wide Band Systems (멀티밴드 UWB 시스템의 무선성능 분석에 관한 연구)

  • Choi, Seok;Kim, Gil-Gyeom;Kwack, Jun-Ho;Kim, Hak-Sun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.12A
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    • pp.951-957
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    • 2003
  • The analysis of RF performance requirement conditions on communication system is critical indicator to predict the performance of system. UWB(Ultra Wide Band) system which the standard is not established yet is difficult to derive the precise system performance requirement condition. Also, there are differences between conventional UWB system and multi-band system about RF performance requirement condition. In this thesis, the differences are analyzed and performance requirement conditions of multi-band UWB system are described on the basis of the differences. Throughput, maximum transmit power, and sensitivity of multi-band UWB system is varied with respect to the number of Sub-Bands. In addition, because of Multi-path effect, if PRF(Pulse Repetition Frequency) is changed, the Multi-path link margin is happened to compensate for Multi-path Energy Loss which is contributed by increasing of the Link Margin. According to Multi-path Margin, the variation of the resistance with respect to sensitivity and interference signal is observed and analyzed through the simulation.

Design and Implementation of Robustness Distributed RTLS in Dense Environment (밀집 환경에 적합한 신뢰성 있는 분산형 RTLS 시스템의 설계 및 구현)

  • Jang, Hyun-Sung;Choi, Hoon;Jung, Yeon-Su;Baek, Yun-Ju
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.2B
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    • pp.287-295
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    • 2010
  • RTLS used to track the location of object or person in real time. However, if there are a lot of tags and readers, the conventional single RTLS server may fail to estimate location of tags. And if the server cannot receive the tags signal due to pass-loss or NLOS from more than three readers, the server fail to estimate location of tags. In this paper, we propose a special reader which embeds RTLS location engine for distributed RTLS. And by using multi-directional antenna, alleviating multi-path effect and allowing estimate tag's location only using two readers. We also implement the system, we can reduce server packet 16times and get the all results of location estimate in single second. We achieved the location error within 1m.