• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.231-238
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• 2007

This paper describes the availability of the forthcoming integrated GNSS(Global Navigation Positioning System) positioning that includes GPS(Global Positioning System), Galileo, and QZSS(Quasi-Zenith Satellites System). We built a signal propagation model that identifies direct, multipath, and diffraction signals, using the principles of specular reflection and ray tracing technique. The signal propagation model was combined with 3D GIS(three-dimensional geographic information system) in order to measure the satellite visibility and positioning error factors, such as the number of visible satellites, average elevation of visible satellites, optimized DOP(dilution of position) values, and the portion of multipath-producing satellites. Since Galileo and QZSS will not be fully operational until 2010, we used a simulation in comparing GPS and GNSS positioning for a $1km{\times}1km$ developed area in Shinjuku, Tokyo. To account for local terrain variation. we divided the target area into 40,000 $5m{\times}5m$ grid cells. The number of visible satellites and that of multipath-free satellites will be greatly increased in the integrated GNSS environment while the average elevation of visible satellites will be higher in the GPS positioning. Much decreased PDOP(position dilution of precision) values indicate the appropriate satellite/user geometry of the integrated GNSS; however, in dense urban areas, multipath mitigation will be more important than the satellite/user geometry. Thus, the efforts for applying current technologies of multipath mitigation to the future GNSS environment will be necessary.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2007.04a
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• pp.73-76
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• 2007

The Global Positioning System(GPS)is an advanced navigation satellite system for determination to position. It can provide three-dimensional positioning, in dependent of weater, 24 hours per day. This paper described the Field DGPS program Using PDA can help a field work and compute the TM rectangular coordinates, compared the output of the Field DGPS program with the results of surveying using EDM(electronic distance measurement).

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.245-250
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• 2022

As location-based services using the Global Navigation Satellite System (GNSS) are diversified, concerns about the vulnerability of GNSS to radio disturbance and deception are also growing. Accordingly, countries that own and operate GNSS, such as the United States, Russia, and Europe, are also developing additional navigation systems that can compensate for GNSS' weaknesses. Among them, an R-Mode system that transmits navigation signals using an infrastructure that transmits differential GNSS (DGNSS) information using signals from the medium frequency band currently in operation is being developed in Europe and Korea. Since 2020, Korea has improved four DGNSS transmission stations, including Chungju, Eocheongdo, Palmido, and Socheongdo, to transmit R-Mode signals and test navigation performance in some parts of the West Sea. In this paper, we intend to establish a testbed for measuring the distance of R-Mode signals currently being transmitted and analyze the results. It is confirmed that the distance measurement performance varies depending on the antenna type, diurnal variation, and propagation path of the signal.

• 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.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.286-290
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• 2011

LBS(Location Based System) is the essential technology of ubiquitous market and utilizes the GNSS(Global Navigation Satellite). GNSS includes GPS of USA, Galileo of Europe Union, QZSS of Japan, Compass of China, and IRNSS of India. Related researches have recently been conducted. Once the satellite is launched, the maintenance such as modification and verification of its function is difficult. Therefore, before the launch of satellites, more precise and concrete verification of performance and operations are needed. In order to do this, hardware testbed may be developed. but software simulators can provide more flexible and cost effective simulation results. These simulators should provide the essential function handling all kinds of error features experienced upon propagation of the GNSS signal. In this paper, we present a design and implementation results of a window-based simulator applying the modeling of various error features for several GNSS.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.200-209
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• 2022

Providing real-time location information is emerging as a major goal of the national industry. In order to provide such real-time location information (3D spatial information), it is essential to develop a technology for a satellite positioning method. Therefore, the country continues to make efforts to increase satisfaction with the needs of consumers by introducing the Network RTK GNSS method. In this study, among the Network RKT GNSS(Global Navigation Satellite System) methods provided by the National Geographic Information Service, continuous observation and single observation were measured at the integrated reference point using VRS(Virtual Reference Station) and FKP(Flӓachen-Korrektur Parameter) to evaluate accuracy. In addition, we aim to maximize efficiency by presenting accuracy on the rapidly increasing Network RTK GNSS method in the field.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.2
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• pp.41-47
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• 2019

Recently, number of intentional jamming has increased significantly. If GNSS jammers are activated, user receivers can be largely influenced due to the vulnerable characteristic of the GNSS (Global Navigation Satellite System) signal. When the reception power of the jamming signal and that of the navigation signal are similar, the C/A (Coarse Acquisition) chip delay error can occur in the delay locked loop. To evaluate the jamming effect, a new measurement model is formulated based on previous research works. The new model explains how the jamming to signal ratio affects the ranging measurement accuracy and other parameters. To evaluate the validity of the newly formulated model, the experiment results of the previous research works under actual jamming environment are utilized. By evaluating the consistency of the carrier-to-noise ratio (C/N0) and the position error with the actual jamming environment, the validity of the newly formulated model is verified.

• Journal of Navigation and Port Research
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• v.38 no.2
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• pp.121-126
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• 2014

This paper suggests a new algorithm to provide low-cost GPS modules with DGPS service, which corrects the error vector in the already-calculated position by projecting range corrections to position domain using the observation matrix calculated from the satellite elevation and azimuth angle in the NMEA GPGSV data. The algorithm reduced the horizontal and vertical RMS error of U-blox LEA-5H module from 1.8m/5.8m to 1.0m/1.4m during the daytime. The algorithm has advantage in improving the performance of low-cost module to that of DGPS receiver by a software update without any correction in hardware, therefore it is expected to contribute to the vitalization of the future high-precision position service infrastructure by reducing the costumer cost and vender risk.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.3
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• pp.101-108
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• 2019

Due to recent improvements in computer processing speed and image processing technology, researches are being actively carried out to combine information from camera with existing GNSS (Global Navigation Satellite System) and dead reckoning. In this study, developed a vision-based positioning assistant algorithm to estimate the distance to the object from stereo images. In addition, GNSS/on-board vehicle sensor/vision based positioning algorithm is developed by combining vision based positioning algorithm with existing positioning algorithm. For the performance analysis, the velocity calculated from the actual driving test was used for the navigation solution correction, simulation tests were performed to analyse the effects of velocity precision. As a result of analysis, it is confirmed that about 4% of position accuracy is improved when vision information is added compared to existing GNSS/on-board based positioning algorithm.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.1
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• pp.85-92
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• 2024

This study develops a Global Positioning System (GPS) Code Multipath Grid Map (CMGM) of each individual domestic reference station from the extracted code multipath of measurement data. Multipath corresponds to signal reflection/refraction caused by obstacles around the receiver antenna, and it is a major source of error that cannot be eliminated by differencing. From the receiver-independent exchange format (RINEX) data for two days, the associated code multipath of a satellite tracking arc is extracted. These code multipath data go through bias correction and interpolation to yield the CMGM with respect to the azimuth and elevation angles. The effect of the CMGM on multipath mitigation is then quantitatively analyzed to improve the Root Mean Square (RMS) of averaged pseudo multipath. Furthermore, the single point positioning (SPP) accuracy is analyzed in terms of the RMS of the horizontal and vertical errors. During two weeks in February 2023, the RMSs of the averaged pseudo multipath for five reference stations decreased by about 40% on average after CMGM application. Also, the SPP accuracies increased by about 7% for horizontal errors and about 10% for vertical errors on average after CMGM application. The overall quantitative analysis indicates that the proposed approach will reduce the convergence time of Differential Global Navigation Satellite System (DGNSS), Real-Time Kinematic (RTK), and Precise Point Positioning (PPP)-RTK correction information in real-time to use measurement data whose code multipath is corrected and mitigated by the CMGM.