• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.331-336
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• 2002

Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, navigation activities and accurate surveying measurements since 90s in the last century due to it advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically. This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China′s "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industrialized trade in China, gives an account of the writers′ vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology′s application and its industrialization future in China.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.403-409
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• 2015

The Quasi-Zenith Satellite System (QZSS), a dedicated regional Japanese satellite system currently under development, was designed to complement the performance of the Global Positioning System (GPS). The high elevation angle of the QZSS satellite is expected to enhance the effectiveness of GPS in urban environments. Thus, the work described in this paper, aimed to investigate the effect of QZSS on GPS performance, by processing the GPS and QZSS measurements recorded at the Bohyunsan reference station in South Korea. We used these data, to evaluate the satellite visibility, carrier-to-noise density (C/No), performance of single point positioning, and Dilution of Precision (DOP). The QZSS satellite is currently available over South Korea for 19 hours at an elevation angle of more than 10 degrees. The results showed that the impact of the QZSS on users' vertical positioning is greatest when the satellite is above 80 degrees of elevation. As for Precise Point Positioning (PPP) performance, the combined GPS/QZSS kinematic PPP was found to improve the positioning accuracy compared to the GPS only kinematic PPP.

• Journal of Positioning, Navigation, and Timing
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• 제7권1호
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• pp.15-24
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• 2018

This study analyzed positioning accuracy of the multi-differential global navigation satellite system (DGNSS) algorithm that integrated GPS, GLONASS, and BDS. Prior to the analysis, four sites of which satellite observation environment was different were selected, and satellite observation environments for each site were analyzed. The analysis results of the algorithm performance at each of the survey points showed that high positioning performance was obtained by using DGPS only without integration of satellite navigation systems in the open sky environment but the positioning performance of multi-DGNSS became higher as the satellite observation environments degraded. The comparison results of improved positioning performance of the multi-DGNSS at the poor reception environment compared to differential global positioning system (DGPS) positioning results showed that horizontal accuracy was improved by 78% and vertical accuracy was improved by 65% approximately.

• Journal of Positioning, Navigation, and Timing
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• 제4권4호
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• pp.205-211
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• 2015

The Global Navigation Satellite System (GNSS) is undergoing dramatic changes. Nowadays, much more satellites are transmitting navigation data at more frequencies. A multi-GNSS analysis is performed to improve the positioning accuracy by processing combined observations from different GNSS. The multi-GNSS technique can improve significantly the positioning accuracy. In this paper, we present a combined Global Positioning System (GPS), the GLObal NAvigation Satellite System (GLONASS), the China Satellite Navigation System (BeiDou), and the Quasi-Zenith Satellite System (QZSS) standard point positioning (SPP) method to exploit all currently available GNSS observations at Mokpo (MKPO) station in South Korea. We also investigate the multi-GNSS data recorded at MKPO reference station. The positioning accuracy is compared with several combinations of the satellite systems. Because of the different frequencies and signal structure of the different GNSS, intersystem biases (ISB) parameters for code observations have to be estimated together with receiver clocks in multi-GNSS SPP. We also present GPS/GLONASS and GPS/BeiDou ISB values estimated by the daily average.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.125-129
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• 2006

Japan has been investigating a new satellite based positioning system called Quasi-Zenith Satellite System (QZSS). Since the improvement of positioning availability in urban area is one of the most important advantages of the QZSS, multipath mitigation is a key factor for the QZSS positioning system. Therefore, Japan Aerospace Exploration Agency (JAXA) and GNSS Inc. have commenced the R&D of a pseudolite, which transmits the next-generation signal such as BOC(1,1), in order to evaluate the effect of multipath on the new signal. A prototype BOC pseudolite was developed in 2005, and ground tests showed a capability of generating proper pseudorange. Also, preliminary flight experiments using a pseudo quasi-zenith satellite, a helicopter on which the pseudolite is installed, were conducted in early 2006, and the BOC-type correlation function was monitored in real time.

• 대한원격탐사학회지
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• 제19권3호
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• pp.181-190
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• 2003

Since the operation of the first satellite-based navigation service, satellite positioning has played an increasing role in both surveying and geodesy, and has become an indispensable tool for precise relative positioning. However, in some situations, e.g. at a low angle of elevation, the use of satellites for navigation is seriously restricted because obstacles like buildings and mountains can block signals. As a mean to resolve this problem, the quasi-zenith satellite system has been proposed as a next-generation satellite navigation system. Quasi-zenith satellite is a system which simultaneously deploys several satellites in a quasi-zenith geostationary orbit so that one of the satellites always stay close to the zenith if viewed from a specific point on the ground of East Asia. Thus, if a position measurement function compatible with CPS is installed in the quasi-zenith and stationary satellites, and these satellites are utilized together with the CPS, four satellites can be accessed simultaneously nearly all day long and a substantial improvement in position measurement, especially in metropolitan areas, can be achieved. The purpose of this paper is to evaluate the effectiveness of quasi-zenith satellite system on positioning accuracy improvement through simulation by using precise orbital information of the satellites and a three-dimensional digital map. Through this developed simulation system, it is possible to calculate the number of simultaneously visible satellites and available area for positioning without the need of actual observation. Furthermore, this system can calculate the Dilution Of Precision (DOP) and the error distribution.

• 한국지리정보학회지
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• 제6권4호
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• pp.51-58
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• 2003

GPS를 대표로 하는 위성측위시스템은 GIS 데이터베이스 구축을 위한 데이터 취득에 있어서 중요한 역할을 하고 있다. 또한 최근의 위성측위 기술의 발전은 보다 빠르고 쉽고 경제적인 방법으로 대상물의 정확한 위치 정보의 취득을 가능하게 하였다. 그러나 도시공간 환경에 있어서는 수많은 도시공간 구조물들로 인해 측위위성과 수신기 사이의 시통이 제한됨으로써 정확한 GIS 데이터베이스 구축에 필요한 신뢰성 있는 위치정보 취득이 곤란하게 된다. 또한 대부분의 GIS 데이터 생성과 갱신의 소요가 도시공간을 중심으로 이루어지고 있음을 고려할 때, 이와 같은 도시공간에서의 위성측위를 통한 위치정보 취득의 곤란은, 정확하고 신속함을 필요로 하는 GIS 데이터 취득에 심각한 문제를 야기하게 된다. 따라서, 본 연구에서는 실제 도시공간에의 위치정보 취득을 위한 위성측위 환경을 평가하기 위해 차량측정장치를 사용하여 실제 도시공간을 대상으로 현장 실험을 수행하였다. 본 연구를 통하여 기존의 GPS 만을 이용한 위성측위 방식에서는 위치정보 데이터 취득에 한계성이 있다는 것을 파악할 수 있었으며, 이 결과는 향후 새로운 보완 측위 기술 연구분야에서 유용한 기초자료로서 활용될 수 있을 것으로 사료된다.

• 전자공학회논문지
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• 제49권10호
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• pp.23-33
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• 2012

본 논문은 위성항법시스템을 이용한 정밀 단독측위에 관한 연구이다. 위성항법시스템이 가지고 있는 내재적인 문제점인 장애물 등 여러 가지 환경 요인으로 인해 신호를 수신할 수 없는 경우 음영지역과 위치오차 증가 등에 관한 연구논문이다. 논문에서는 다양한 수신기의 성능 분석과 대도로 중앙, 대도로 측면, 주택가, 고층 건물 주변의 골목길 등 다양한 환경에 따른 위성수와 DOP(Dilution of Precision)변화 그리고 위치오차의 변화 등을 분석하였다. 그리고 환경 변화에 따른 위치오차 발생 범위와 오차 원인을 파악하여, 위성항법시스템의 신뢰성과 안정성을 높이는데 그 목적이 있다.

• 한국위성정보통신학회논문지
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• 제8권2호
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• pp.62-67
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• 2013

최근 위성항법장치를 활용한 GPS(Global Positioning System)를 통해 위성에서 보내는 위치정보를 이용하여 사용자에게 다양한 서비스를 제공하는 위치기반서비스가 이뤄지고 있다. 하지만 위성신호의 특성상 고층 건물이 밀집되어 있는 도심과 같은 지역에서는 반사, 굴절로 인해 오차를 가진 위치정보를 얻게 된다. 본 연구과제는 GPS 위치신호 오차를 보정하기 위해 사용자의 이동방향 정보의 방향벡터를 계산하여 분산된 위치좌표를 방향벡터 위로 보정하는 후처리 알고리즘을 제안하고자 한다. 도심지역에서의 차량주행 실험을 통하여 기존 GPS 보다 평균 11.1m(43%)의 정확도 향상을 통하여 제안한 후처리 알고리즘의 우수성을 입증하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.751-756
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• 2002

Since the operation of the first satellite-based navigation services, satellite positioning has played an increasing role in both surveying and navigation, and has become an indispensable tool for precise relative positioning. However, in some situations, e.g. at a low angle of elevation, the use of satellites for navigation is seriously restricted because obstacles like buildings and mountains can block signals. As a mean to resolve this problem, the quasi-zenith satellite system has been proposed as a next-generation satellite navigation system. Quasi-zenith satellite is a system which simultaneously deploys several satellites in a quasi-zenith geostationary orbit so that one of the satellites always stay close to the zenith if viewed from a specific point on the ground of East Asia. Thus, if a position measurement function compatible with GPS is installed in the quasi-zenith and stationary satellites, and these satellites are utilized together with the GPS, four satellites can be accessed simultaneously nearly all day long and a substantial improvement in position measurement, especially in metropolitan areas, can be achieved. The purpose of this paper is to evaluate the effectiveness of quasi-zenith satellite system on positioning accuracy improvement through simulation by using precise orbital information of the satellites and a three-Dimensional digital map. Through this simulation system, it is possible to calculate the number of simultaneously visible satellites and available area of the positioning without the need of actual observation.