• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.243-251
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• 2021

Real-Time Kinematic (RTK) is a phase-based differential GNSS technique and uses additional observations from permanent reference stations to mitigate or eliminate effects like atmospheric delays or satellite clocks and orbit errors. In particular, as the position accuracy required in the fields of autonomous vehicles and drones is gradually increasing, the demand for RTK-based precise navigation that can provide cm-level position is increasing. Recently, with the rapid growth of the open-source software market, the use of open-source software for building navigation system of unmanned vehicles, which is difficult to mount an expensive GNSS receivers, is gradually increasing. RTKLIB is an open-source software package that can perform RTK positioning and is widely used for research and education purposes. However, since the performance and stability of RTK algorithm of RTKLIB is inevitably inferior to that of commercial GNSS receivers, users need to verify whether RTKLIB can satisfy the navigation performance requirements of unmanned vehicles. Therefore, in this paper, the performance evaluation of the RTK positioning algorithm of RTKLIB was performed using GNSS observation data acquired in a dynamic environment. Therefore, in this paper, the RTK positioning performance of RTKLIB was evaluated using GNSS observation data acquired in a dynamic environment. Our results show that the current RTK algorithm of RTKLIB is not suitable for precise navigation of unmanned vehicles.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.91-96
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• 2004

More recently, multiple reference based RTK GPS techniques(VRS : Virtual Reference System) are becoming increasingly important for many precise GPS applications in many countries to overcome the constrained distance limitations of standard RTK systems. The precision of the position solutions of the rover receiver is closely connected with that of the corresponding virtual reference points(VRPs). The objective of this paper is to investigate the accuracy and performance of the VRPs on the test network for static positioning in post processing mode. For this, some VRPs at the inside and outside of test network have made in post mode, and the overall analysis results were presented by comparing the solution for the VRPs from the existed GPS reference station with the true values of the coordinates used to produce the observation data. The results show the reasonable accuracies of VRPs in the network area by using the VRS concept in post mode.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.55-63
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• 2013

Network-RTK GPS positioning technique based on national CORS(Continuous Operating Reference Station) and wireless internet access as like VRS and FKP was developed to overcome the limitations of traditional RTK technique. In Korea, NGII(National Geographic Information Institute) provides network-RTK service based on 51 CORS and mobile internet network. The purpose of this study is the accuracy evaluation of the height determined by GPS VRS technique based on network-RTK, So, in this study GPS VRS positioning was accomplished through 1st level BM line located at Sancheong~Jinju and $2^{nd}$ level BM line located at Geochang~Sancheong and the average error of the each BM line was calculated as 2.15cm and 1.80cm respectively. This result shows that GPS VRS height positioning can be used in $3^{rd}$ and 4th public BM leveling and also work regulation is needed to apply the GPS VRS height positioning.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.2
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• pp.135-142
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• 2013

Recently, it is a pretty well known way to compute GPS/INS using Continuously Operating Reference Station (CORS) and Network-based RTK for obtaining Exterior Orientation (EO) parameters of aerial photogrammetry. In this study, it is way to compute Exterior Orientation (EO) parameters using ground base stations, using Continuously Operating Reference Station (CORS) broadcast orbits and International GNSS Service (IGS) rapid orbits. And the residuals of Exterior Orientation (EO) parameters were computed based on the results of ground base station. As a result, the case of using SmartBase to obtain Exterior Orientation (EO) parameters was showed the high accuracy of X, Y, K more than using Continuously Operating Reference Station (CORS) of National Geographic Information Institute (NGII). Also, distance and direction of Continuously Operating Reference Station (CORS) of National Geographic Information Institute (NGII) from ground base station affected Exterior Orientation (EO) parameters. And different forms of residuals were shown according to the aerial photo courses.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_1
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• pp.463-469
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• 2013

In addition to the VRS-RTK service, FKP-RTK service launched recently in Korea however unlike VRS, it is not yet applied to various surveying tasks. VRS system is operated in two way communication over the mobile Internet. When user send rover position data to network RTK server and the server provides correction data to users continuously. It causes to increase communications load and makes delaying or failure in data transmission depends on server capacity and number of concurrent users. In contrast, since FKP system is one way communication system, user only receives correction data and area correction parameters for the selected Continuous Reference Station from the server. Thus, there is no limitation to the number of concurrent users in FKP system and it would be more efficient than VRS system in terms of economic. To this end, we performed FKP-RTK test for Unified Control Points and Urban Control Points where are located at 5 regions in Korea to evaluate the accuracy. As a result, almost of FKP positioning data are in error range of ${\pm}6.2cm$ in horizontal and it would be enough for construction survey such as for earth work in limited except precise structure survey.

• Journal of Cadastre & Land InformatiX
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• v.47 no.1
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• pp.95-110
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• 2017

The network RTK surveying has been widely used in the field of cadastral surveys in recent years, and its use is gradually expanding. As a result of the implementation of GPS static surveys by civilian companies in accordance with the progress of the cadastral surveys and gradual civilian transfer plans and cadastral surveys, there has been an increase in the number of civilian companies performing surveys. In this paper, we describe the process of applying the results of analysis of conformity using the network RTK site calibration function on the local coordinate system to the GPS static surveying of the cadastral reference points in Anyang city. In addition, the measurement results of the network RTK site calibration function and the results of the GPS static surveying network reconciliation in the local coordinate system were compared, and the performance was determined within 0.04m maximum of RMSE(Root Mean Square Error), and further study on the application method is needed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.4
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• pp.277-283
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• 2013

GPS RTK surveying has an issue that the positioning error increases as the base line distance between the reference station and rover station increases. However, nowadays, an accuracy assessment that can handle such issue is surely required because of the modernization of GLONASS, Galileo project, and other improvements of satellite receiving conditions. Therefore, in this research, we compared and analyzed data sets collected with the CORS network, placed at NGII and NDGPS, using Internet RTK surveying in different satellite receiving conditions. As a result, there was a negative effect on the positioning accuracy as the base line distance increases. Furthermore, we could collect quantitative data of the accuracy of RTK surveying. When national-wide GNSS system is fully established, this result will contribute the growth of various GNSS industries including survey industries and land survey industries.

• 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 Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.267-275
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• 2007

Nowadays, it grows bigger the importance of water resource management, and so, hydrographic surveying technology in river is important because it serves basic data about river environment. And, also, the application field of GPS has been increased and expected to be more increased because of the change of the geodetic reference system to World Geodetic System. In this study, hydrographic surveying in Hwang river in Geochang is accomplished by RTK GPS and Total Station and they are compared and analyzed the both results. The section profile in river is made by Hec-Ras program and CAD. The results show it can be saved 15.3% in surveying times and the amount of surveying works can be enlarged 42.5%. And the standard error between RTK results with calibration and the results without calibration turned out as 2.1 cm. So we have a conclusion that RTK GPS is more efficient surveying method than total station in hydrographic surveying in river.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.574-583
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• 2013

The coastal area, which is managed by local governments, geographically, culturally and economically has been transformed into more influential space. In recent years, new type of fusion researches about coastal areas that have economic, cultural and engineering aspects, have been conducted. In this study, the multiple observations information was used to analyze change of Ilsan beach shoreline which is located in Dong-gu, Ulsan, Korea. For the shoreline analysis, we used VRS-RTK(Virtual Reference System by Real-Time Kinematic) GPS survey, aerial photograph, terrestrial LiDAR survey and fixed reference station survey. Specially fixed reference station method was suggested for shoreline observation and maintenance. In the case of Ilsan beach shoreline, according to the result of multiple observations information, coastline erosion(6~12m) appeared in medium and lower part and sedimentation(3~14m) in the upper part of coastline.