• Journal of Positioning, Navigation, and Timing
• /
• v.5 no.4
• /
• pp.181-191
• /
• 2016

A Satellite Based Augmentation System (SBAS) provides differential correction and integrity information through geostationary satellite to users in order to reduce Global Navigation Satellite System (GNSS)-related errors such as ionospheric delay and tropospheric delay, and satellite orbit and clock errors and calculate a protection level of the calculated location. A SBAS is a system, which has been set as an international standard by the International Civilian Aviation Organization (ICAO) to be utilized for safe operation of aircrafts. Currently, the Wide Area Augmentation System (WAAS) in the USA, the European Geostationary Navigation Overlay Service (EGNOS) in Europe, MTSAT Satellite Augmentation System (MSAS) in Japan, and GPS-Aided Geo Augmented Navigation (GAGAN) are operated. The System for Differential Correction and Monitoring (SDCM) in Russia is now under construction and testing. All SBASs that are currently under operation including the WAAS in the USA provide correction and integrity information about the Global Positioning System (GPS) whereas the SDCM in Russia that started SBAS-related test services in Russia in recent years provides correction and integrity information about not only the GPS but also the GLONASS. Currently, LUCH-5A(PRN 140), LUCH-5B(PRN 125), and LUCH-5V(PRN 141) are assigned and used as geostationary satellites for the SDCM. Among them, PRN 140 satellite is now broadcasting SBAS test messages for SDCM test services. In particular, since messages broadcast by PRN 140 satellite are received in Korea as well, performance analysis on GPS/GLONASS Multi-Constellation SBAS using the SDCM can be possible. The present paper generated correction and integrity information about GPS and GLONASS using SDCM messages broadcast by the PRN 140 satellite, and performed analysis on GPS/GLONASS Multi-Constellation SBAS performance and APV-I availability by applying GPS and GLONASS observation data received from multiple reference stations, which were operated in the National Geographic Information Institute (NGII) for performance analysis on GPS/GLONASS Multi-Constellation SBAS according to user locations inside South Korea utilizing the above-calculated information.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.8
• /
• pp.1951-1958
• /
• 2015

The paper is focused on not only the system characteristics of BeiDou, China GNSS, but also the statistic analysis based on its real data received from the BeiDou's satellite navigation messages. The 6-7 satellites, which are more than minimum number of 4 satellites to obtain 3-D position, are available for receiving navigation signal in stable case. It was also verified that the available satellites are deviated to specific coordinate and their signals are still unstable. Only as long as the received signal with the high stability, the precision of the BeiDou navigation satellite navigation system was identified with 5m level in deviation. The Beidou system is expected to be rising as a darkhorse in the future of the global satellite navigation area.

• Journal of Satellite, Information and Communications
• /
• v.1 no.1
• /
• pp.48-53
• /
• 2006

A K-SBAS (Korean Satellite Based Augmentation System) is proposed as one of the space infrastructure. The proposed system considers the existed elements to the utmost for the most economical SBAS construction. As reference system the current DGPS (differential global positioning system) network is investigated. Space segment is investigated based on the COMS-1 (Communications, Oceanographic, and Meteorological Satellite-1). While bus system of COMS-1 can be kept to minimum change, the communication payload of needed, crucial parts such as software, man power can be easily secured through the DGPS network operation heritage.

• Journal of Satellite, Information and Communications
• /
• v.12 no.4
• /
• pp.72-77
• /
• 2017

The Satellite Based Augmentation System (SBAS) broadcasts to users integrity and correction information for Global Navigation Satellite System (GNSS) such as GPS and GLONASS using geostationary orbit (GEO) satellites. In accordance with the recommendation of the International Civilian Aeronautical Organization (ICAO) to introduce SBAS until 2025, a Korean SBAS system development / construction project is underway with the Ministry of Land, Transport and Maritime Affairs. Korea Augmentation Satellite System (KASS) is a high precision GPS correction system which is composed of KASS Reference Station (KRS), KASS Processing Station (KPS), KASS Uplink Station (KUS), KASS Control Station (KCS) and GEO satellites. In this paper, we provided the conceptual design of the KASS uplink station, which is composed of the Signal Generator Section (SGS) and the Radio-Frequency Section (RFS), and interface between the KASS ground sector and the GEO satellite.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.947-952
• /
• 2007

EU is in the process of developing a new european global navigation satellite system - Galileo project - which technologies and capitals from member states of EU are put into, after determining to set up a separate GPS against that of US late in the 1990s. Galileo system is commercial global navigation satellite system, which allows other else nations outside of EU to participate in system development and operation, different from GPS. Korea also decided to join in the project on February in 2005. Galileo system provide 5 Services - Open Service, Safety of Life, Commercial Service, Public Regulated Service, Search and Rescue Service, and especially it can be applicable to safety-critical areas, and is to provide its part of services certified. In this paper, we are to compare the services of Galileo system, and to present necessary factors to be considered, and the applicability to use the Galileo system in safety-critical application areas, such as train control system

• Journal of Aerospace System Engineering
• /
• v.4 no.1
• /
• pp.19-22
• /
• 2010

The accuracy and integrity of global navigation satellite systems (GNSS) can be improved by using GNSS augmentation systems. Large ionospheric spatial gradient, during ionosphere storm, is a major threat for using GNSS augmentation systems by increasing the spatial decorrelation between a reference system and users. Ionosphere decorrelation behavior can be analyzed by using dual frequency GPS data. GNSS receivers have their own biases, called inter-frequency bias (IFB) between dual(P1 and P2) frequencies and they must be accurately estimated before computing ionosphere delays. GPS network data in Korea is used to compute each receiver's IFB, and their estimation accuracy and variability are analyzed. IFB estimation methodology to apply for ionosphere gradient analysis is discussed.

• Journal of Positioning, Navigation, and Timing
• /
• v.5 no.4
• /
• pp.213-219
• /
• 2016

Most existing studies on the wide-area differential global positioning system (WADGPS) employed a grid ionosphere model for error correction in the ionospheric delay. The present study discusses the application of satellite-based ionospheric delay model that provides an error model as a plane function with regard to individual satellites in order to improve accuracy in the WADGPS. The satellite-based ionospheric delay model was developed by Stanford University in the USA. In the present study, the algorithm in the model is applied to the WADGPS system and experimental results using measurements in the Korean Peninsula are presented. Around 1 m horizontal accuracy was exhibited in the existing planar fit grid model but when the satellite-based model was applied, correction performance within 1 m was verified.

• Journal of Positioning, Navigation, and Timing
• /
• v.1 no.1
• /
• pp.1-6
• /
• 2012

For a Global Positioning System (GPS) receiver, it is known that a Vector Delay Locked Loop (DLL) in which the code signals of each satellite are tracked in parallel by using navigation results shows better performance in the aspect of the tracking accuracy and the robustness than that of a Scalar DLL. However, the quantitative analysis and the logical grounds for that performance enhancement of the Vector DLL are not sufficient. This paper, therefore, proposes the structure of the GPS receiver with the Vector DLL and analyzes the performance of it. The tracking and the positioning accuracy of the Vector DLL are theoretically analyzed and confirmed by simulation results. From the simulation results, it can be seen that the tracking and positioning accuracy has been improved about 30% in case that the receiver is static and the positioning is conducted for every Pre-detection Integration Time (PIT) while C/N0 is 45 dB-Hz.

• Journal of Advanced Navigation Technology
• /
• v.19 no.1
• /
• pp.1-6
• /
• 2015

Due to the rapid increase in air traffic worldwide, ICAO has replaced the existing navigation equipment with equipment based on satellite navigation. As a part of that work, ICAO was planning to replace conventional takeoff and landing service using ILS with GBAS. Unlike ILS, GBAS which uses precision approach service inducing aircraft to airport and satellite based augmentation system providing precise position information service surrounding airport is capable of providing a required performance by only a system, regardless of the number of systems, and has an advantage that it is possible curved approach. In this paper, fuel reduction of ILS approach procedures and GBAS curved approach procedures is estimated and determined by flight test in Taean Airport.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.5
• /
• pp.313-319
• /
• 2021

The national geodetic reference frame of Korea was adopted in 2003, which is referenced to ITRF (International Terrestrial Reference Frame) 2000 at the epoch of January 1, 2002. For precise positioning based on the satellites, it should be thoroughly maintained to the newest global reference frame. Other than plate tectonic motion, there are significant events or changes such as earthquakes, antenna replacement, PSD (Post-Seismic Deformation), seasonal variation etc. We processed three years of GNSS (Global Navigation Satellite System) data(60 NGII CORS stations, 51 IGS core stations) to produce daily solutions minimally constrained to ITRF. From the time series of daily solutions, the sites with unexpected discontinuity were identified to set up an event(mostly antenna replacement). The combined solution with minimum constraints was estimated along with the velocity, the offsets, and the periodic signals. The residuals show that the surrounding environment also affects the time series to a certain degree, thus it should be improved eventually. The transformation parameters to ITRF2014 were calculated with stability and consistency, which means the national geodetic reference frame is properly aligned to the global reference frame.