• Title, Summary, Keyword: GNSS

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Accuracy Analysis of GPS Ellipsoidal Height Determination in Accordance with the Surveying Conditions (관측조건에 따른 GPS 타원체고 결정의 정확도 분석)

  • Lee, Suk Bae;Auh, Su Chang
    • Journal of Korean Society for Geospatial Information Science
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    • v.23 no.4
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    • pp.67-74
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    • 2015
  • GNSS/Leveling technology makes it possible to get geoidal height geometrically using GNSS and Leveling technology. GNSS/Geoid technology refers to a technology for obtaining orthometric height by subtracting geoidal height achieved by Geoid technology from ellipsoidal height achieved by GNSS technology. The purpose of this study is to verify the accuracy of the ellipsoidal height determination in order to verify the accuracy of the orthometric height determination by the GNSS/Geoid technology. For the study, a test bed was selected in Kyungnam province and GNSS Static surveying was accomplished in the test bed and then the GNSS data was processed in accordance with various analysis conditions. So, it was verified the accuracy of the ellipsoidal heights determination in accordance with the surveying conditions under the GNSS Static surveying. According to the research results, to ensure the 3cm goal accuracy of the ellipsoidal height determination, it should be surveyed by four fixed points on the survey area periphery and more than two hours of the GNSS occupation time, And also, it was found that should be limited to a baseline distance of 20km under the GNSS Static surveying.

Implementation of Vehicle Navigation System using GNSS, INS, Odometer and Barometer

  • Park, Jungi;Lee, DongSun;Park, Chansik
    • Journal of Positioning, Navigation, and Timing
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    • v.4 no.3
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    • pp.141-150
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    • 2015
  • In this study, a Global Navigation Satellite System (GNSS) / Inertial Navigation System (INS) / odometer / barometer integrated navigation system that uses a commercial navigation device including Micro Electro Mechanical Systems (MEMS) accelerometer and gyroscope in addition to GNSS, odometer information obtained from a vehicle, and a separate MEMS barometer sensor was implemented, and the performance was verified. In the case of GNSS and GNSS/INS integrated navigation system that are generally used in a navigation device, the performance would deteriorate in areas where GNSS signals are not available. Therefore, an integrated navigation system that calculates a better navigation solution in areas where GNSS signals are not available compared to general GNSS/INS by correcting the velocity error of GNSS/INS using an odometer and by correcting the cumulative altitude error of GNSS/INS using a barometer was suggested. To verify the performance of the navigation system, a commercial navigation device (Softman, Hyundai Mnsoft, http://www.hyundai-mnsoft.com) and a barometer sensor (ST Company) were installed at a vehicle, and an actual driving test was performed. To examine the performance of the algorithm, the navigation solutions of general GNSS/INS and the GNSS/INS/odometer/barometer integrated navigation system were compared in an area where GNSS signals are not available. As a result, a navigation solution that has a smaller position error than that of GNSS/INS could be obtained in the area where GNSS signals are not available.

An Analysis of Spoofing Effects on a GNSS Receiver Using Real-Time GNSS Spoofing Simulator (실시간 GNSS 기만 시뮬레이터를 이용한 위성항법수신기에서의 기만 영향 분석)

  • Im, Sung-Hyuck;Im, Jun-Hyuck;Jee, Gyu-In;Heo, Mun-Beom
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.2
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    • pp.113-118
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    • 2013
  • In this paper, spoofing effects on a GNSS receiver were analyzed. The spoofer (spoofing device) was classified to two categories. One is an active spoofer and the other is a passive spoofer. The active spoofer was considered for analysis. For the analysis of spoofing effects on a GNSS receiver, a real-time GNSS spoofing simulator was developed. The simulator was consisted with two parts which are a baseband signal generation part and a RF up-conversion part. The first GNSS baseband signal was generated according to spoofing parameters such as range, range rate, GNSS navigation data, spoofing to GNSS signal ratio, and etc. The generated baseband signal was up-converted to GNSS L1 band. Then the signal transmitted to a GNSS signal. For a perfect spoofing, a spoofer knew an accurate position and velocity of a spoofing target. But, in real world, that is not nearly possible. Although uncertainty of position and velocity of the target was existed, the spoofer was operated as an efficient jammer.

Multi-GNSS Kinematic Precise Point Positioning: Some Results in South Korea

  • Choi, Byung-Kyu;Cho, Chang-Hyun;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.1
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    • pp.35-41
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    • 2017
  • Precise Point Positioning (PPP) method is based on dual-frequency data of Global Navigation Satellite Systems (GNSS). The recent multi-constellations GNSS (multi-GNSS) enable us to bring great opportunities for enhanced precise positioning, navigation, and timing. In the paper, the multi-GNSS PPP with a combination of four systems (GPS, GLONASS, Galileo, and BeiDou) is analyzed to evaluate the improvement on positioning accuracy and convergence time. GNSS observations obtained from DAEJ reference station in South Korea are processed with both the multi-GNSS PPP and the GPS-only PPP. The performance of multi-GNSS PPP is not dramatically improved when compared to that of GPS only PPP. Its performance could be affected by the orbit errors of BeiDou geostationary satellites. However, multi-GNSS PPP can significantly improve the convergence speed of GPS-only PPP in terms of position accuracy.

Study on for Simulation of GNSS Signal Generation (위성항법 신호생성 시뮬레이터 구현을 위한 신호생성 알고리즘 연구)

  • Kim, Tae-Hee;Lee, Jae-Eun;Lee, Sang-Uk;Kim, Jae-Hoon;Hwang, Dong-Hwan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.11
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    • pp.1148-1156
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    • 2009
  • ETRI has developed GNSS digitized IF signal generator for providing test and evaluation environment for various software level application and navigation algorithm in Global Navigation Satellite System(GNSS). GNSS digitized IF signal generator provides two main capabilities, GPS and Galileo raw data generation and digitized IF signal generation. GNSS digitized IF signal generator consists of five main modules which are GNSS Satellite Orbit Simulation Module, Navigation Message Generation Module, Error Generation Module, GNSS IF Signal Generation Module, and Message & Signal Steering Module. We verified the signal generated by the GNSS signal generation algorithm using software receiver for generation of signal brother to real GNSS signal.

Development of Precision Positioning and Fine Displacement Monitoring Based on GNSS (GNSS 기반의 정밀측위 및 미세변위 모니터링 개발)

  • Yeon, Sang-Ho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.3
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    • pp.145-152
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    • 2017
  • In this paper, GNSS(global navigation satellite system) to monitoring the fine for the construction of structure displacement based on satellite communications signals of GNSS. At the same time on USN(ubiquitous sensor network) and proposed a new approach to precise positioning by analyzing the results. A major construction structure for the safety diagnosis and prevent disaster from the risk of collapse. Precision measurement methods to mm level GNSS in that case and experiments in the application of new technologies that can most commonly used to replace the current through the permanent. The way a GNSS baseline and tested it on to prove. As a result, at our country at precise positioning and fine displacement monitoring application virtual reference station(VRS) in a GNSS mm of a margin of error of horizontal and vertical directions can be found.

Accuracy Analysis of Orthometric Heights Based on GNSS Static Surveying (GNSS 정지측량을 통한 표고 산출 정확도 분석)

  • Shin, Gwang-Soo;Han, Joong-Hee;Kwon, Jay Hyoun
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.32 no.5
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    • pp.527-537
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    • 2014
  • In 2013, NGII(National Geographic Information Institute) has developed and provided the KNGeoid13(Korean National Geoid Model 2013) to support the fundamental computation of GNSS-derived orthometric height. In this study, the adjusted ellipsoidal height, the sum of geoidal height and height by the leveling, is applied to calculate the GNSS-derived orthometric height without the local bias, based on GNSS static surveying and KNGeoid13. The mean of errors in GNSS-derived orthometric heights could be verified with the leveling data, which was actually less than 0.5 cm with using the adjusted ellipsoidal heights, but 3 cm by calculating differences between ellipsoidal heights and geoidal heights. By analyze the accuracy of GNSS-derived orthometric height depending on the duration of observation, we could realized 95% of data shows less than 4 cm accuracy, when the GNSS survey conducting for 4 hours spread over two days, but while the case of GNSS survey conducting for 4 hours and 2 hours respectively, resulted in 95% of data less than 5cm level of accuracy. Also, if the ambiguity is fixed, less than 10cm of accuracy could be obtained at 95% of data for only 30 minutes GNSS survey over a day. Following the study, we expected that the height determination by GNSS and geoid models can be used in the public benchmark surveying.

Positioning Precision Improvement of Multi-GNSS Kinematic PPP Using WMN Method

  • Choi, Byung-Kyu;Yoon, Ha Su;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.4
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    • pp.205-210
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    • 2017
  • Multi-Global Navigation Satellite System (GNSS) can significantly improve the positioning accuracy and convergence speed. The reliability and availability of multi-GNSS precise point positioning (PPP) is steadily increasing with the rapid development of GNSS satellites. In this study, multi-GNSS PPP analysis is performed to compare the positioning precision by processing the observations from different GNSS systems (GPS, GLONASS, Galileo and BeiDou). To improve the positioning performance of the multi-GNSS PPP, we employed the weighed measurement noise (WMN) method. After applying WMN method to multi-GNSS PPP, positioning precision is improved by approximately 26.3% compared to the GPS only solutions, and by approximately 9.1% compared to combined GPS, GLONASS, and Galileo PPP.

Implementation and Test of Simulator for Analyzing Effect of GNSS Jamming (GNSS 전파교란 영향분석 시뮬레이터 구현 및 시험)

  • Joo, Inone;Sin, Cheonsig
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.24 no.4
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    • pp.1-5
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    • 2016
  • As a dependency on Global Navigation Satellite System (GNSS) becomes increase in various applications, its reliability has been very important. However, in South Korea, Global Positioning System (GPS) jamming incident happened four times since 2010. GNSS signal is so weak that it is highly susceptible to all types of the jamming. GNSS jamming can cause serious damage in the safety-critical applications based on the GNSS. In this paper, we present the GNSS jamming signal propagation prediction simulator based on ITU-R P.1546 model. This simulator is developed for preventing or reducing the damage from the GNSS jamming attack by predicting the jamming propagation strength based on the geographical information in Korean peninsula.

Development and Validation of an Integrated GNSS Simulator Using 3D Spatial Information (3차원 공간정보를 이용한 통합 GNSS 시뮬레이터 개발 및 검증)

  • Kim, Hye-In;Park, Kwan-Dong;Lee, Ho-Seok
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.27 no.6
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    • pp.659-667
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    • 2009
  • In this study, an integrated GNSS Simulator called Inha GNSS Simulation System (IGSS) using 3D spatial information was developed and validated. Also positioning availability and accuracy improvement were evaluated under the integrated GNSS environment using IGSS. GPS and GLONASS satellite visibility predictions were compared with real observations, and their frequency of error were 6.4% and 7.5%, respectively. To evaluate positioning availability and accuracy improvement under the integrated GNSS environment, the Daejeon government complex area was selected to be the test site because the area has high-rise buildings and thus is susceptible to signal blockages. The test consists of three parts: the first is when only GPS was used; the second is when both GPS and GLONASS were simulated; and the last is when GPS, GLONASS, and Galileo were used all together. In each case, the number of visible satellites and Dilution Of Precision were calculated and compared.