• Title/Summary/Keyword: GPS DOP

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Analysis for Influence and Geometry of GPS/Galileo System (GPS/Galileo 시스템의 기하구조 및 영향 분석)

  • Lee Jae-One
    • Journal of Navigation and Port Research
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    • v.29 no.8 s.104
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    • pp.763-770
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    • 2005
  • Global Navigation Satellite System (GNSS) has become an indispensable tool for providing precise position, velocity and time information for many applications like traditional surveying and navigation etc. However, Global Positioning System (GPS), which was developed and is maintained and operated by the U.S. Department of Defence (DoD), has monopolized the world industry and market, and hence there exists the situation that most of GNSS users absolutely depend upon the GPS. In order to overcome the monopoly, some countries, such as Russia, Japan and European Union (EU), have developed their own GNSSs, so-called GLONASS, JRANS and Galileo systems. Among them, the most prospective system in near future is EU's Galileo system scheduled to launch in 2008. This research has focused on the next generation GNSS system based on GPS and Gralileo system with developing a GNSS simulation software, named as GIMS2005, which generates and analyzes satellite constellation and measurements. Based on the software, a variety of simulation tests have been carried out to recognize limits of GPS-only system and potential benefits of integrated GPS/Galileo positioning. Geometry simulation results have showed that comparing with GPS-only case, the number qf visual satellites, Dilution of Precision (DOP) values, internal reliabilities and external reliabilities.

2013년도 동해안 전파교란 측정에 관한 연구

  • Yu, Hyeon-Geun
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2013.10a
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    • pp.345-345
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    • 2013
  • 한미 키리졸브 훈련에 따라 북한의 GPS 전파교란에 대비하여 동해안 속초지역에 운항중인 한빛호에 고성능 GNSS 수신기와 안테나를 설치 후 전파교란을 측정(2013. 3. 14 ~ 3. 21)하여, 원시정보(GPS/GLONASS의 추적 위성수, 위성배치(DOP), 위성신호세기)를 분석한 결과 GPS/GLONASS 위성신호와 유사한 주파수 전파 간섭은 발생하지 않은 것으로 측정 되었으며, 향후 지속적 측정을 통하여 위성신호와 비슷한 주파수 대역의 전파교란 대비 필요.

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Analysis of 3D GIS- Based GNSS Visibility at Urban Area (도심에서의 3차원 GIS 기반 위성항법시스템 가시성 분석)

  • Yoo, Kyung-Ho;Kang, Tae-Sam;Sung, Sang-Kyung;Lee, Eun-Sung;Jeong, Seong-Kyun;Sin, Cheon-Sig;Lee, Sang-Uk;Lee, Young-Jae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.12
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    • pp.1095-1100
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    • 2007
  • Visibility of the satellite navigation is related to a environmental condition of a receiver. Obstacles like buildings and trees in urban areas can block signals and have effects on accuracy and reliability of positioning. This paper presents a method of creating 3D analysis model of urban canyon of Seoul using three-Dimensional digital map. Analysis techniques of visible satellites with Ray-Polygon Collision Detection and validation of algorithm through field tests are discussed. We have compared and analyzed the visibility of GPS and Galileo with respect to separate and simultaneous tracking in view of DOP (Dilution of Precision) using the 3D GIS digital map.

Study on Performance Analysis Technique of GPS Receiver According to Vehicle Attitude Change (항체 자세 변화에 따른 GPS 수신기의 성능분석 기법 연구)

  • Yoo Ki-Jeong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.7 no.2 s.17
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    • pp.13-21
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    • 2004
  • GPS is widely used in various applications since GPS receivers are capable of measuring precise position and velocity in any weather condition for a relatively low cost. However, GPS requires more than four simultaneously visible GPS satellites for optimal performance. In high-motion, high-attitude-changing applications, there exist some situations where less than four satellites are visible or where the dilution of precision (DOP) is high. In this paper, we propose a simulation algorithm that predicts the performance of GPS navigation according to changes in vehicle attitude. We have compared simulation results with experimental results, where simulation results of the proposed algorithm are shown to closely match actual experimental data. This algorithm could be used to predict GPS navigational performance and to determine optimal GPS antenna position.

GPS(Global Positioning System) 추적 성능 분석

  • No, Gi-Hong;Seong, Tae-Gyeong
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.2
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    • pp.431-434
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    • 2006
  • 현재 사용되는 디지털 신호처리 방식의 GPS(Global Positioning System) 수신기는 최소의 RF 블록만을 이용하여 모든 디지털 신호 처리를 소프트웨어로 수행하고 있다. 소프트웨어 GPS수신기의 장점으로는 디지털 신호처리 과정이 모두 소프트웨어로 구현되어 있기 때문에 새로운 구현 방식이나 알고리즘을 적용할 시, 하드웨어 변경은 필요가 없게 되고, 소프트웨어 재설계만으로 가능하다. GPS 수신기의 Tracking module 성능은 DLL discriminator function과 FLL discriminator function의 Algorithm에 의해서 영향을 받게 된다. DLL discriminator function algorithm에는 dot-product 와 normalized dot-product 방법 등이 있으며, FLL discriminator function algorithm에는 sign(dot)(cross)-product 와 cross-product 그리고 ATAN 방법이 있다. 이러한 discriminator function들은 algorithm에 따라 input error에 대한 discriminator의 출력 값을 일정한 범위에서의 차이를 나타내게 되면서 ranging accuracy에서 차이가 나타나게 된다. 본 논문에서는 Nordnav 소프트웨어 GPS 수신기를 이용하여 DLL discriminator algorithm과 FLL discriminator algorithm의 성능을 비교, 분석을 하고 Tracking accuracy, sensibility, 그리고 multipath rejection에 대해서 알아보고자 한다.

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The Movement Monitoring of Structures using GPS

  • Shon, Howoong;Oh, Seok Hoon;Kim, Youngkyung
    • Journal of the Korean Geophysical Society
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    • v.7 no.4
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    • pp.325-330
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    • 2004
  • For the monitoring of structures, it is desirable for the measurement system to deliver equal precision in all components. When using GPS the accuracy, availability, reliability and integrity of the position solutions is very dependent on the number and geometric distribution of the available satellites. Therefore the positioning precision is not the same in all there component, and large variations (in positioning) precision can be expected during a 24-hour period. This situation becomes worse when the line-of-sight to GPS satellites becomes obstructed, such as in urban environments. Pseudolites can be sed to augment GPS and improve a geometrically weak satellite constellation. The use of pseudolites as supplement(s) of GPS for the movement measurement of bridges is demonstrated in this paper. It is shown that pseudollites can improve the vertical position components.

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Analysis of Sky-View-Factor based Dilution of Precision for Evaluation of GNSS Performance in Land Road Environment (육상교통환경 위성항법 성능 예측을 위한 Sky-View-Factor 기반 Dilution of Precision 분석)

  • Hong, Woon-Ki;Choi, Kwang-Sik;Lee, Eun-Sung;Im, Sung-Hyuck;Heo, Moon-Beom
    • Journal of Advanced Navigation Technology
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    • v.16 no.6
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    • pp.944-951
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    • 2012
  • The conventional indexes for describing the GNSS positioning performance such as satellite visibility, dilution of precision (DOP) and signal to noise ratio is very useful in open sky, however, they are not useful in the land road environment. In this paper new index is suggested for describing the GNSS positioning performance for the road environment. The new index is called Sky View based DOP (SVDOP). SVDOP is derived referring the Sky-View-Factor (SVF). The usefulness is analyzed by comparing the SVDOP and SVF in land road environment after the singularity points are selected and SVDOP is calculated.

KOMPSAT-1 Satellite Orbit Control using GPS Data

  • Lee, Jin-Ho;Baek, Myuog-Jin;Koo, Ja-Chun;Yong, Ki-Lyuk;Chang, Young-Keun
    • International Journal of Aeronautical and Space Sciences
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    • v.1 no.2
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    • pp.43-49
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    • 2000
  • The Global Positioning System (GPS) is becoming more attractive navigation means for LEO (Low Earth Orbit) spacecraft due to the data accuracy and convenience for utilization. The anomalies such as serious variations of Dilution-Of-Precision (DOP), loss of infrequent 3-dimensional position fix, and deterioration of instantaneous accuracy of position and velocity data could be observed, which have not been appeared during the ground testing. It may cause lots of difficulty for the processing of the orbit control algorithm using the GPS data. In this paper, the characteristics of the GPS data were analyzed according to the configuration of GPS receiver such as position fix algorithm and mask angle using GPS navigation data obtained from the first Korea Multi-Purpose Satellite (KOMPSAT). The problem in orbit tracking using GPS data, including the infrequent deterioration of the accuracy, and an efficient algorithm for its countermeasures has also been introduced. The reliability and efficiency of the modified algorithm were verified by analyzing the effect of the results between algorithm simulation using KOMPSAT flight data and ground simulator.

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The Effect of Altitude Errors in Altitude-aided Global Navigation Satellite System(GNSS) (고도를 고정한 GNSS 위치 결정 기법에서 고도 오차의 영향)

  • Cho, Sung-Lyong;Han, Young-Hoon;Kim, Sang-Sik;Moon, Jei-Hyeong;Lee, Sang-Jeong;Park, Chan-Sik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.10
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    • pp.1483-1488
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    • 2012
  • This paper analyzed the precision and accuracy of the altitude-aided GNSS using the altitude information from digital map. The precision of altitude-aided GNSS is analysed using the theoretically derived DOP. It is confirmed that the precision of altitude-aided GNSS is superior to the general 3D positioning method. It is also shown that the DOP of altitude-aided GNSS is independent of altitude bias error while the accuracy was influenced by the altitude bias error. Furthermore, it is shown that, since the altitude bias error influenced differently to each pseudorange measurement, the effect of the altitude bias error is more serious than clock bias error which does not influence position error at all. The results are evaluated by the simulation using the commercial RF simulator and GPS receiver. It confirmed that altitude-aided GNSS could improve not only precision but also accuracy if the altitude bias error are small. These results are expected to be easily applied for the performance improvement to the land and maritime applications.