• Title/Summary/Keyword: precise positioning

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Performance Analysis of GPS/BDS Integrated Precise Positioning System Considering Visibility in Urban Environments

  • Noh, Jae Hee;Lee, Sun Yong;Lim, Deok Won;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.8 no.1
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    • pp.31-40
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    • 2019
  • In recent years, Intelligent Transport Systems (ITS) and Autonomous Vehicle Technology have actively studied around the world. In order to achieve the purpose of Advanced Driver Assistance System (ADAS) and Autonomous Vehicle Technology, it must be obtained accurate and reliable positioning. However, the problem of positioning in the urban area is a low position accuracy caused by the reduction of the number of visible satellites due to high buildings. In this paper, we analyzed the availability of precise positioning system in urban area are using GPS/BDS integrated system. For this study, GPS and BDS satellite signals were collected using two low-cost receivers in the open sky and a designed software based platform for precise positioning performance analysis. And we analyzed the precise positioning performance by changing the mask angle considering the urban area. From the results, it can be confirmed that the performance of precise positioning of GPS only and BDS only decrease in the environment where mask angle is $40^{\circ}$ to $45^{\circ}$, however, GPS/BDS integrated system maintains high performance of precise positioning.

Precision Assessment of Near Real Time Precise Orbit Determination for Low Earth Orbiter

  • Choi, Jong-Yeoun;Lee, Sang-Jeong
    • Journal of Astronomy and Space Sciences
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    • v.28 no.1
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    • pp.55-62
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    • 2011
  • The precise orbit determination (POD) of low earth orbiter (LEO) has complied with its required positioning accuracy by the double-differencing of observations between International GNSS Service (IGS) and LEO to eliminate the common clock error of the global positioning system (GPS) satellites and receiver. Using this method, we also have achieved the 1 m positioning accuracy of Korea Multi-Purpose Satellite (KOMPSAT)-2. However double-differencing POD has huge load of processing the global network of lots of ground stations because LEO turns around the Earth with rapid velocity. And both the centimeter accuracy and the near real time (NRT) processing have been needed in the LEO POD applications--atmospheric sounding or urgent image processing--as well as the surveying. An alternative to differential GPS for high accuracy NRT POD is precise point positioning (PPP) to use measurements from one satellite receiver only, to replace the broadcast navigation message with precise post processed values from IGS, and to have phase measurements of dual frequency GPS receiver. PPP can obtain positioning accuracy comparable to that of differential positioning. KOMPSAT-5 has a precise dual frequency GPS flight receiver (integrated GPS and occultation receiver, IGOR) to satisfy the accuracy requirements of 20 cm positioning accuracy for highly precise synthetic aperture radar image processing and to collect GPS radio occultation measurements for atmospheric sounding. In this paper we obtained about 3-5 cm positioning accuracies using the real GPS data of the Gravity Recover and Climate Experiment (GRACE) satellites loaded the Blackjack receiver, a predecessor of IGOR. And it is important to reduce the latency of orbit determination processing in the NRT POD. This latency is determined as the volume of GPS measurements. Thus changing the sampling intervals, we show their latency to able to reduce without the precision degradation as the assessment of their precision.

Precise Point Positioning using the BeiDou Navigation Satellite System in South Korea

  • Choi, Byung-Kyu;Cho, Chang-Hyun;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.4 no.2
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    • pp.73-77
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    • 2015
  • Global Positioning System (GPS) Precise Point Positioning (PPP) has been extensively used for geodetic applications. Since December 2012, BeiDou navigation satellite system has provided regional positioning, navigation and timing (PNT) services over the Asia-Pacific region. Recently, many studies on BeiDou system have been conducted, particularly in the area of precise orbit determination and precise positioning. In this paper PPP method based on BeiDou observations are presented. GPS and BeiDou data obtained from Mokpo (MKPO) station are processed using the Korea Astronomy and Space Science Institute Global Navigation Satellite System (GNSS) PPP software. The positions are derived from the GPS PPP, BeiDou B1/B2 PPP and BeiDou B1/B3 PPP, respectively. The position errors on BeiDou PPP show a mean bias < 2 cm in the east and north components and approximately 3 cm in the vertical component. It indicates that BeiDou PPP is ready for the precise positioning applications in the Asia-Pacific region. In addition, BeiDou tropospheric zenith total delay (ZTD) is compared to GPS ZTD at MKPO station. The mean value of their difference is approximately 0.52 cm.

A Study on Precise Positioning with Doppler Measurements for Ground Transportation System (도플러 측정치를 이용한 육상교통 환경에 적합한 정밀 측위 기법 연구)

  • Lee, Byung-Hyun;Jee, Gyu-In
    • Journal of Advanced Navigation Technology
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    • v.14 no.5
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    • pp.632-639
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    • 2010
  • Ground Transportation is one of the most required field that users need positioning information Especially, more precise position can make smart traffic management possible and bring convenience to users. By advanced wireless network, cars can receive the GPS information of reference station in any tim e and any where. Thus land vehicles are possible to process precise positioning. In general, for precise positioning code and phase measurements are used. But receivers provide not only code and phase measurements but also doppler measurements and Doppler is direct measurement of velocity. In this paper, because velocity is very important information required in Ground Transportation, precise positioning for Ground Transportation is studied. For precise positioning RTK(Real-Time Kinematic) was used and double differenced doppler measurements were added, As a Result, positioning error by multipath and cycle slip was soften. However there still remained Positioning error. Thus smoothing technique using doppler measurement in position domain is used for softening positioning error.

Development of a Combined GPS/GLONASS PPP Method

  • Choi, Byung-Kyu;Roh, Kyoung-Min;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.3 no.1
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    • pp.31-36
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    • 2014
  • Precise Point Positioning (PPP) is a stand-alone precise positioning approach. As the quality of satellite orbit and clock products from analysis centers has been improved, PPP can provide more precise positioning accuracy and reliability. A combined use of Global Positioning System (GPS) and Global Orbiting Navigation Satellite System (GLONASS) in PPP is now available. In this paper, we explained about an approach for combined GPS and GLONASS PPP measurement processing, and validated the performance through the comparison with GPS-only PPP results. We also used the measurement obtained from the GRAS reference station for the performance validation. As a result, we found that the combined GPS/GLONASS PPP can yield a more precise positioning than the GPS-only PPP.

Network Configuration Design of GNSS Receiving Station for Optimizing Performance of Precise Positioning (정밀 위치결정 성능 최적화를 위한 위성항법 수신국 네트워크 구성)

  • Son, Minhyuk;Kim, Geo-Heon;Lee, Eunsung;Heo, Moon-Beam
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.20 no.4
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    • pp.31-38
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    • 2012
  • In this paper, requirements of GNSS receiver station installation are derived for optimizing the performance of network based GNSS precise positioning by concern of international organization(IGS, NGS) recommendation. Also a analysis method of network based GNSS precise positioning is suggested in order to evaluate the availability depending on various network configurations. To evaluate network candidates, a performance evaluation method is proposed for positioning of users according to a geometric configuration and the baseline distance. After the proposed method is used to Ochang region that is a the test area 6 network candidates are derived and the performance of positioning was analyzed. Finally, Ansung, Gongju, Eumsung, Boeun network configuration was selected as the best positioning performance. An optimal Receiving station network was selected using the proposed method.

The Suggestion of Effective Measurement Techniques for Positioning Under Poor GPS Reference Network Condition

  • Park, Joon-Kyu;Jung, Kap-Yong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.31 no.6_2
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    • pp.539-547
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    • 2013
  • This research is suggesting the most effective positioning method for GPS based positioning when no GPS reference point is available in the neighborhood. For this purpose, we carried out positioning of the IGS realtime observatories in Australia in various conditions. According to the research, we were certainly assured the one reference point with a short baseline length is more effective for differential positioning than multiple reference points with a long baseline distance beyond 1,000km and suggested the precise point positioning based positioning method can be an excellent substitute when no reference point is available around an unknown point. The research result may be used as the basic data for accurate positioning in poor reference point environments, especially in Antarctica.

Expected RGDOP Based Satellite Selection Scheme for Performance Improvement of Precise Float Solution

  • Lee, Sunyong;Lim, Deok Won;Noh, Jae Hee;Lee, Jin Hyuk;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.7 no.4
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    • pp.255-265
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    • 2018
  • In this paper, the positioning performance index is proposed. The proposed index is used to find satellites that degrade positioning performance to improve the positioning performance. To do this, the proposed index is calculated using the code measurement quality and the DOP. And, through the experiment, the effectiveness of the proposed index is confirmed. In the experiment, the quality of the code measurements is analyzed, and the effectiveness of the proposed index is confirmed by comparing with the result of the precise float solution. Finally, it is shown that the precise float solution performance is improved by using the proposed index.

Development of Precise Point Positioning Method Using Global Positioning System Measurements

  • Choi, Byung-Kyu;Back, Jeong-Ho;Cho, Sung-Ki;Park, Jong-Uk;Park, Pil-Ho
    • Journal of Astronomy and Space Sciences
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    • v.28 no.3
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    • pp.217-223
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    • 2011
  • Precise point positioning (PPP) is increasingly used in several parts such as monitoring of crustal movement and maintaining an international terrestrial reference frame using global positioning system (GPS) measurements. An accuracy of PPP data processing has been increased due to the use of the more precise satellite orbit/clock products. In this study we developed PPP algorithm that utilizes data collected by a GPS receiver. The measurement error modelling including the tropospheric error and the tidal model in data processing was considered to improve the positioning accuracy. The extended Kalman filter has been also employed to estimate the state parameters such as positioning information and float ambiguities. For the verification, we compared our results to other of International GNSS Service analysis center. As a result, the mean errors of the estimated position on the East-West, North-South and Up-Down direction for the five days were 0.9 cm, 0.32 cm, and 1.14 cm in 95% confidence level.

National-Wide NETPPI-LT Cluster Design using CORS (상시기준국을 이용한 정밀위치결정 인프라 클러스터 전국단위 설계)

  • Shin, Miri;Ahn, Jongsun;Son, Eunseong;Heo, Moon-Beom
    • Journal of Advanced Navigation Technology
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    • v.22 no.6
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    • pp.577-584
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    • 2018
  • GNSS based transport infrastructure cluster is to broadcast satellite navigation correction information and integrity information capable of precise positioning for land transport users. This makes it possible to do lane-level positioning reliably. However, in order to provide the lane-level positioning and correction information service nationwide, new station sites selection and to build GNSS stations have a heavy cost and a burden for a considerable period of time. In this paper, we propose the cluster design criteria and national-wide network-based precise positioning for land transportation (NETPPI-LT) cluster design for a cluster-based precise positioning. Furthermore, it is analyzed the precise positioning pre-performance of this cluster design based on the spatial error and verified its suitability as the precise positioning pre-performance of the cluster design.