• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.109-113
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• 2003

GPS 상시관측소의 활용과 중요성은 GPS측량에서 폭넓은 사용과 비교적 높은 정확도를 충족시키는 방안으로 점점 가치를 더 하고 있다. 현재 RINEX 포맷 형태로 인터넷 서비스를 하고 있는 GPS 상시관측소의 자료를 이용하여 기준점으로써의 가치를 평가하고 또한 시간과 경비를 줄일 수 있는 방법인 VRS-GPS기법을 연구하고자 한다. 본 연구에서는 임의의 기준국을 설치하여, 기존 삼각점과 GPS 상시관측소를 이용해 관측망을 형성, 그 결과를 비교 고찰하였으며 이 기준국을 RTK-GPS의 고정국으로 하여 실시간 측위를 하였다. 고정국은 전자 가상 기준국인 VRS-RTK 개념으로 가정하고 비교, 검증하였다.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.37-42
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• 2009

The accuracy of RTK GPS is limited by the distance dependent errors from orbit, ionosphere and troposphere, as the distance between the rover and the base station increases in the Real Time Kinematic surveying. To solve this problem, VRS system has installed. This study would estimated the accuracy of cadastral detail surveying, which is used on the VRS RTK instead of Total Station and RTK GPS demand for various equipments and time. As a result of study, the positioning accuracy of the VRS RTK and RTK GPS surveying make no greate difference, as RMSE of VRS RTK surveying is 0.144m and that of RTK GPS surveying is 0.146m and the new method would be more efficient.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.4
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• pp.413-422
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• 2012

After development of GPS in the 1960's, the United States released SA(Selective Availability) in 2000 and then the GPS has become commercialized to the present. The result of repeatedly developed GPS observation, the GPS real-time observation methods is RTK which basically always needs two base stations and has a fault of the accuracy decreasing as the distance between a mobile station and a receiver is increasing. Because of these weakness, VRS method has come out. VRS(Virtual Reference Station) generates the imaginary point near mobile station from several observatory datum of GPS, sets the accurate location of mobile station, thus shows high reliability and mobility. Now, the cadastral datum point is used with azimuth, repetition, and graphical traversing method for traverse network. The result of measurement indicates many problems because of different accomplishment interval given point, restrictions on the length of the conductor, many errors on the observations. So, this study did comparative analysis of the cadastral datum points through VRS method by Continuously Operating Reference Station. Through the above comparative analysis, The comparative result between surveyed result with repetition method through total station observed Cadastral Control Points and surveyed result with VRS-RTK has shown that average error of x-axis is -0.08m, average error of y-axis, +0.07m and average distance error is +0.11m.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.1
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• pp.89-95
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• 2009

The accuracy and efficiency of RTK-GPS is proved through its measurement, but it is not used in cadastral detail surveying, due to low accuracy caused by the trouble of satellite reception in a built-up area and lack of detailed guidelines for practical application. Thus, this study tries to offer detailed directions for the practical use of RTK-GPS by analyzing the application problem of RTK-GPS measurement. As results of the study, for the practical use of RTK-GPS it suggests enactment of regulations, connection of practical RTK-GPS measurement with the existing detail surveying methods, introduction of a VRS method for increasing the arrangement density of reference stations, and integrated use of GPS, GLONASS and Galileo satellites for securing accuracy and stability.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.21-28
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• 2010

The classical RTK System requires that GPS data is transmitted from a single reference receiver to one or more roving units. But its error increase due to distance between reference and rover. VRS(Virtual Reference Station) system, a network of reference stations can be used to isolate the components of these systematic errors and use the resultant corrections to create Virtual Reference Stations at any location within the network. Use of a VRS significantly reduces the effects of systematic errors and improved accuracy. In this study, Network-RTK survey using VRS serviced by NGII(National Geographic Information Institute) was performed and the results were compared with results of total station surveying and notified coordinates of cadastral control points for utilization assessment of VRS.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.3
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• pp.259-267
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• 2020

For real-time precise positioning, N-RTK (Network Real-Time Kinematic) technology is widely used these days. However, the currently operating N-RTK system has a limitation in terms of the number of users. Therefore, if reference points generate correction messages with no limit on the number of users are developed later, it is determined that an appropriate reference point installation interval is required, so that the accuracy of the N-RTK system according to the baseline distance was analyzed. This experiment utilized receivers with varying performance that estimated the rover position, and RTKLIB, an open-source software, is used for processing data. As a result, the rover position was estimated accurately with a high rate of fixed ambiguity for all the receivers. When the reference station with a baseline length of 40 km was used, the vertical RMSE (Root Mean Squared Error) was quite similar to the short baseline case, but only half of the ambiguity fixing rate was achieved. The outlier in the estimated rover position was not observed for the longer baselines in the case of a high-end receiver. It is necessary to analyze the ambiguity fixing and the accuracy of the kinematic positioning with scientific GNSS processing software.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.2 s.29
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• pp.29-35
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• 2004

The plenty of availability and high precision of GPS CORS is the reason why it become important more and more in the fields of surveying widely. In this study, I extracted the arbitrary point's coordinate which is using GPS CORS data, now served in RINEX FORMAT via Inter-Net, with observation network of the existing triangulation and GPS CORS data. Then, with this arbitrary point as reference station RTK GPS was performed. And I will study VRS-GPS concept which reduces the time and cost in the fields of surveying.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.471-480
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• 2018

Accurate target coordinate is very important in military operations especially field artillery's ground-to-ground attack and air-force's air-to-ground attack. DOS(or TAS) is used to acquire target coordinates from long distance. DOS is comprised of LRF and goniometer. LRF measures distance between DOS and target. Goniometer is comprised of azimuth and vertical angular sensors, DMC and internal GPS receiver. DOS must set the position and orientation(finding grid north) before measurement step(target coordinate acquisition). To improve accuracy of target coordinate, VRS RTK and reference point method are proposed in DOS setup step. VRS RTK provides accurate location coordinate with small deviations, providing high accuracy and precision in positioning and orientation. As a result, horizontal coordinate(easting and northing) accuracy is improved from 2.68 mil(C.L. = 0.95) mil to 0.58 mil(C.L. = 0.95).

• Journal of Advanced Navigation Technology
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• v.17 no.4
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• pp.404-412
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• 2013

Network RTK is widely used especially for static applications so far, however, the demand for high accuracy positioning for kinetic users such as land vehicles is growing for safety and convenience reasons. Kinematic users move along the roads and the network where they receive corrections can be changed. Compact Network RTK corrections should keep consistency while network change. In this paper, we introduced a method of generating Compact Network RTK corrections considering network ambiguity level adjustment by formulation of corrections. We verified the proposed method for reference station networks across whole country. We also generated Compact Network RTK corrections using simulation and real GPS data from reference stations in South Korea and evaluated performance of users. As a result, the discontinuity between corrections from two networks reduced to 0.25 cycle from several cycles. And user could achieve less than 8 cm (2DRMS) horizontal position accuracy continuously regardless of network change.