• Journal of Astronomy and Space Sciences
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• v.20 no.3
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• pp.197-204
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• 2003

We demonstrated positioning accuracy of iRTK system, which has been developed by Korea Astronomy Observatory, using a low-price GPS receiver. Each four different baseline positioning tests using the iRTK system, we certified 1-3 meters level positioning accuracy of the iRTK system. While the iRTK is similar to conventional RTK at coverage and accuracy, the iRTK positioning carried out from data processing center. And also, the iRTK system has no limit of data communication coverage because of using wire/wireless Internet. But the iRTK system has a weakness of short available coverage within 5km. Therefore we discussed a plan to adopt VRS (Virtual Reference System) as completion of the iRTK system preparing nation-wide iRTK service in near future.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.2
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• pp.139-147
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• 2008

The positioning accuracies tend to deteriorate as the distance between the rover and the reference station increases in the Real-Time Kinematic (RTK) surveys using Global Positioning System (GPS). To solve this problem, the National Geographic Information Institute (NGII) of Korea has installed Virtual Reference System (VRS), which is one of the network-based RTK systems. In this study, we conducted the accuracy tests of the VRS-RTK surveys. We surveyed 50 control points inside the NGII's GPS Continuously Operating Reference Stations (CORS) network using the VRS-RTK system, and compared the results with the published coordinates to verify the positioning accuracies. We also conducted the general RTK surveys at the same control points. The results showed that the positioning accuracy of the VRS-RTK was comparable to that of the general RTK, because the horizontal positioning accuracy was 3.1 cm while that of general RTK was 2.0 cm. Also the vertical positioning accuracy of VRS-RTK was 6.8 cm.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.479-484
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• 2015

Network RTK is a precise positioning technique using carrier phase correction data from reference stations within the network, and is constantly being researched for improved performance. However, the study for the system accuracy has been performed but system integrity research has not been done as much as system accuracy, because network RTK has been mainly used on surveying for static or kinematic positioning. In this paper, adequate monitoring system for network RTK is designed as basis research for integrity monitoring on network RTK. To this, fault tree on network RTK is analyzed, and a countermeasure is prepared to detect and identify the each fault items. Based these algorithms, monitoring system to use on central processing facility is designed for network RTK service.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.2
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• pp.87-94
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• 2019

The Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) positioning has been widely used in geodesy, surveying, and navigation fields. RTK can benefit enormously from the integration of multi-GNSS. In this study, we develop a GPS/BeiDou Navigation Satellite System (BDS) RTK integration algorithm for long baselines ranging from 128 km to 335 km in South Korea. The positioning performance with GPS/BDS RTK, GPS-only RTK, and BDS-only RTK is compared in terms of the positioning accuracy. An improvement of positioning accuracy over long baselines can be found with GPS/BDS RTK compared with that of GPS-only RTK and that of BDS-only RTK. The positioning accuracy of GPS/BDS RTK is better than 2 cm in the horizontal direction and better than 5 cm in the vertical direction. A lower Relative Dilution of Precision (RDOP) value with GPS/BDS integration can obtain a better positional precision for long baseline RTK positioning.

• Spatial Information Research
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• v.14 no.2 s.37
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• pp.211-221
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• 2006

GLONASS(Global NAvigation Satellite System) using the satellite information on 19,100km altitude supplies the location information similar method with GPS. Therefore, many researches study in combination GPS and GLONASS. This research compares with deciding coordination of one unit parcel using RTK-GPS and RTK-GPS/CLONASS. Then we examine the possibility of RTK-GPS/GLONASS for determining parcel coordinate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.455-458
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• 2006

The Real Time Kinematic (RTK) technique is the most productive and accurate GPS positioning method today, as it can be determinate position within few centimeters instantly. This method is widely used for applications such as surveying, structure monitoring and machine guidance etc. In order to perform RTK processing for large scale systems (i.e. precise vehicle monitoring with many rovers), many expensive RTK receivers and same number of bidirectional communication units have to be installed to collect observation data communicate with the reference site and monitor its RTK solutions. Moreover, if applications require remote control or apply sensing instruments, we have to install computers at each rover. To limit expense and complexity of system management with a large number of rovers, we have developed server based RTK processing platform to share RTK function for all rovers. The system can be process many GPS stations with a single personal computer. we have also developed a specialized dual frequency GPS receiver unit without on-board RTK processing capability to reduce receiver cost in order to demonstrate the advantage of our server based RTK platform. This paper describes the concept of our server based RTK platform and specialized GPS receiver unit with existing applications in Japan.

• Spatial Information Research
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• v.18 no.5
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• pp.1-11
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• 2010

Since January 2009, Seoul Metro Government(SMG) is operating own Network RTK Systems connecting four(4) GNSS Reference Stations which are installed inside Seoul Metro City area. SMG is currently providing VRS data service via wireless internet for Network-RTK and RINEX data observed from GNSS Reference Stations. This paper will discuss utilization of data available from SMG Network-RTK System for various applications, and present the test results on practicalities of Virtual RINEX data. For the utilization of data available from SMG Network- RTK system, 1)NTRIP data delivery of GNSS realtime observables streaming and converting to RINEX at receiving side, 2) monitoring deformation of bulky structures using GNSS observation were discussed. In addition to those discussion, 3) broadcasting VRS correction data for job site via radio modem after acquiring such correction data on-line using NTRIP based GNSS Internet Radio from SMG Network-RTK System were introduced. For the test results on practicalities of Virtual RINEX data, 1) the post-processing results of the GNSS observation data on a certain point with GNSS Reference Station data have been compared to the post-processing results of Virtual RINEX data on the same point generated from SMG Network-RTK System, and 2) VRS RTK positioning results for a certain point and post-processing results of Virtual RINEX data for the point were compared. The results showed only a few mm difference, and the high possibility for using Virtual RINEX data for post-processing applications.

• Korean Journal of Remote Sensing
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• v.18 no.6
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• pp.345-358
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• 2002

DGPS(Differential Global Positioning System) and RTK(Real time Kinematic) are in one of today's most widely used surveying techniques. However surveying with these techniques is restricted by the distance between reference and rover station, and it is difficult to process data in realtime by their own organizational limitation in precise measurement of positioning. To meet these new demands, in this paper, new DGPS and RTK correction data services through the Internet and PSTN(Public Switched Telephony Network) have been proposed. For this purpose, a DGPS and RTK error correction data transmission system is implemented for long-distance using the Internet and PSTN which allows a mobile user at which the rover receiver is located to receive the correction data from the reference in realtime, and analyzed and compared with DGPS and RTK performances by experiments through the Internet and PSTN for the distance and the time.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.418-426
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• 2022

Unlike OSR(observation space representation), the SSR(state space representation) augmentation system is suitable for a one-way broadcasting service because it provides the same corrections to all users in the service area. Due to this advantage, several GNSS(global navigation system) systems such as Galileo, BDS(beidou navigation satellite system), QZSS(quasi zenith satellite system) are establishing PPP (precise point positioning)/PPP-RTK precision positioning services based on SSR messages. Therefore, in this paper, we try to understand the trends of satellite-based PPP/PPP-RTK correction services by analyzing the system configurations, characteristics, and precise positioning performance of satellite-based SSR correction broadcasting services.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.97-101
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• 2003

Among GPS methods, first of all, we used RTK GPS to analyze the precision of monitoring and then on the basis of it, we developed a monitoring system using RTK GPS when we measured the behavior of main tower of a suspension bridge by using RTK GPS method and IMU, which was an inertia navigation system. Comparing a deviation between observation value using IMU and RTK GPS, X axis was 1mm, Y axis 1mm and Z axis 2.21mm. It turned out that it was possible to monitor and measure structures by using RTK GPS method. Besides, in order to manage the structures and prevent their disaster, the transformed monitoring, which used dynamic RTK GPS measurement method, was applied in real time. It was verified that it could be used as transformed monitoring measurement method for massive structures.