• Journal of electromagnetic engineering and science
• /
• v.14 no.3
• /
• pp.299-305
• /
• 2014

A wideband circularly polarized (CP) antenna with a single feed is proposed for use in global navigation satellite systems. Its primary radiation elements are composed of two orthogonal bowtie dipoles, which are equipped with double-printed vacant-quarter rings to allow direct matching of the antenna to a single $50-{\Omega}$ coaxial line and to produce CP radiation. The crossed bowtie dipole is appropriately incorporated with a planar metallic reflector to produce the desired unidirectional radiation pattern as well as to achieve a wideband characteristic in terms of impedance matching and axial ratio (AR) bandwidths. The designed antenna was fabricated and measured. The prototype antenna with an overall 1.2-GHz frequency size of $0.48{\lambda}_o{\times}0.48{\lambda}_o{\times}0.25{\lambda}_o$ produced a measured ${\mid}S_{11}{\mid}$<-10 dB bandwidth of 1.05-1.79 GHz and a measured 3-dB AR bandwidth of 1.12-1.64 GHz. It also showed right-hand CP radiation with a small gain variation (${\pm}0.3dB$) and high radiation efficiency (>93%) over the operational bandwidth.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.6 no.12
• /
• pp.631-638
• /
• 2016

GNSS(Global Navigation Satellite System) such as GPS(Global Positioning System), GLONASS(GLObal NAvigation Satellite System) has been used in various fields for construction of geospatial inforamtion. But RTK or VRS method for high accuracy has some bad points like requirement of additional GNSS device and internet. So, this methods are difficult to take advantage of field survey. In this study, In this study, experiments using DGPS handheld devices and smart devices that can maximize mobility through was to suggest ways to improve the efficiency of field survey work. As a results, field survey work with smart devices is difficult to apply the limits of accuracy yet. On the other hand, DGPS has been found possible to determine the position accuracy within 1m. If DGPS is used in related work can greatly improve the efficiency of field survey work, which is currently much is done by hand, it is expected to serve as the basis for a structured GIS data management.

• 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 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.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.6
• /
• pp.1059-1068
• /
• 2021

In urban areas, GPS(Global Positioning System)/GNSS(Global Navigation Satellite System) signals are blocked or distorted by structures such as buildings, which limits positioning. To compensate for this problem, in this paper, fingerprinting-based positioning using RSRP(: Reference Signal Received Power) information of LTE signals is performed. The W-KNN(Weighted - K Nearest Neighbors) technique, which is widely used in the positioning step of fingerprinting, yields different positioning performance results depending on the similarity distance calculation method and weighting method used in correlation. In this paper, the performance of the fingerprinting positioning according to the techniques used in correlation is comparatively analyzed experimentally.

• Journal of Positioning, Navigation, and Timing
• /
• v.10 no.4
• /
• pp.363-369
• /
• 2021

Since the Global Navigation Satellite System (GNSS) signal received from the low Earth orbit (LEO) satellite is only affected by the upper ionosphere, the magnitude of the ionospheric delay of Global Positioning System (GPS) signal received from ground user is different. Therefore, the ground-based two-dimensional ionospheric model cannot be applied to LEO satellites. The NeQuick model used in Galileo provides the ionospheric delay according to the user's altitude, so it can be used in the ionospheric model of the LEO satellites. However, the NeQuick model is not suitable for space receivers because of the high computational cost. A simplified NeQuick model with reduced computing time was recently presented. In this study, the computing time of the NeQuick model and the simplified NeQuick model was analyzed based on the GPS Klobuchar model. The NeQuick and simplified NeQuick model were applied to the GNSS data from GRACE-B, Swarm-C, and GOCE satellites to analyze the performance of the ionospheric correction and positioning. The difference in computing time between the NeQuick and simplified NeQuick model was up to 90%, but the difference in ionospheric accuracy was not as large as within 4.5%.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.2
• /
• pp.71-76
• /
• 2006

With the rapid development of spatial infrastructure in US, Europe, Japan, China and India, there is no doubt that the next generation Global Navigation Satellite System (GNSS) will improve the integrity, accuracy, reliability and availability of the position solution. GNSS is becoming an essential element of personal, commercial and public infrastructure and consequently part of our daily lives. However, the applicability of GPS in supporting a range of location-sensitive applications such as location based services in an urban environment is severely curtailed by the interference of the 3D urban settings. To characterize and gain in-depth understanding of such interferences and to be able to provide location-based optimization alternatives, a high-fidelity 3D urban model of Melbourne CBD built with ArcGIS and large scale high-resolution spatial data sets is used in this study to support a comprehensive simulation of current and future GNSS signal performance, in terms of signal continuity, availability, strength, geometry, positioning accuracy and reliability based on a number of scenarios. The design, structure and major components of the simulator are outlined. Useful time-stamped spatial patterns of the signal performance over the experimental urban area have been revealed which are valuable for supporting location based services applications, such as emergency responses, the optimization of wireless communication infrastructures and vehicle navigation services.

• 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 Navigation and Port Research
• /
• v.28 no.1
• /
• pp.23-29
• /
• 2004

This paper deals with Reed-Solomon Coding for EUROFIX system EUROFIX is an integrated navigation and communication system, which combines Differential GNSS and Loran-C EUROFIX transmits DGNSS(Differential Global Navigation Satellite Systems) (data by pulse position modulation of Loran-C pulses. Loran-C system is regarded as a satellite backup system in recent. And now, it is important to detect and correct much errors in communication systems. Error corrections or correction algorithm is actively studied nowadays because of this. In this paper, we study and design encoder and decoder of Reed Solomon Code using Finite Galois Field Fourier Transformation for error corrections in EUROFIX data transmission. Through extensive simulation, the designed Reed Solomon code is shown to be effective for error correction in EUROFIX data transmission.