• 한국위성정보통신학회논문지
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• 제3권2호
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• pp.32-37
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• 2008

Global Navigation Satellite System (GNSS) is been developing in many countries. The satellite navigation system has the importance in economic and military fields. For utilizing satellite navigation system properly, the technology of GNSS Ground Station is needed. GNSS Ground Station monitors the signal of navigation satellite and analyzes navigation solution. This study deals with the navigation software for GNSS Ground Station. This paper will introduce the navigation solution algorithm for GNSS Ground Station. The navigation solution can be calculated by the code-carrier smoothing method, the Kalman-filter method, the least-square method, and the weight least square method. The performance of each navigation algorithm in this paper is presented.

• 한국항행학회논문지
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• 제20권4호
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• pp.305-313
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• 2016

ICAO (International Civil Aviation Organization)는 GNSS (global navigation satellite system)를 이용하는 PBN (performance based navigation) 도입을 권고하였다. 우리나라도 PBN 로드맵을 수립하여 항공분야에서 GNSS를 이용할 수 있는 환경을 갖추려 시도하고 있으며, 2014년 10월 한국형 SBAS (satellite-based augmentation system) 개발을 위해 KASS (Korea augmentation satellite system) 사업을 본격적으로 착수하였다. 항공기가 GNSS를 이용하기 위해서는 수신기와 같은 항법장비를 탑재해야 한다. GNSS 항법장비는 항로, 이륙 도착, 접근 등 비행 단계에서 사용되기 때문에 장비의 규격은 다양하고 각각 별도로 그 기능과 성능을 규정하고 있다. 이 논문에서는 현재까지 제정된 항공용 GNSS 장비 표준안과 규정된 항법장비 및 인터페이스 규격에 대해 분석하여 정리하였다. KASS 개발 구축 시 비행시험 및 비행절차 개발 등 항공용 GNSS 탑재장비 등이 요구되는 곳에 활용성이 있을 것으로 기대한다.

• Journal of Positioning, Navigation, and Timing
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• 제4권2호
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• pp.43-55
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• 2015

In the case of satellite navigation positioning, the shielding of satellite signals is determined by the environment of the region at which a user is located, and the navigation performance is determined accordingly. The accuracy of user position determination varies depending on the dilution of precision (DOP) which is a measuring index for the geometric characteristics of visible satellites; and if the minimum visible satellites are not secured, position determination is impossible. Currently, the GLObal NAvigation Satellite system (GLONASS) of Russia is used to supplement the navigation performance of the Global Positioning System (GPS) in regions where GPS cannot be used. In addition, the European Satellite Navigation System (Galileo) of the European Union, the Chinese Satellite Navigation System (BeiDou) of China, the Quasi-Zenith Satellite System (QZSS) of Japan, and the Indian Regional Navigation Satellite System (IRNSS) of India are aimed to achieve the full operational capability (FOC) operation of the navigation system. Thus, the number of satellites available for navigation would rapidly increase, particularly in the Asian region; and when integrated navigation is performed, the improvement of navigation performance is expected to be much larger than that in other regions. To secure a stable and prompt position solution, GPS-GLONASS integrated navigation is generally performed at present. However, as available satellite navigation systems have been diversified, finding the minimum satellite constellation combination to obtain the best navigation performance has recently become an issue. For this purpose, it is necessary to examine and predict the navigation performance that could be obtained by the addition of the third satellite navigation system in addition to GPS-GLONASS. In this study, the current status of the integrated navigation performance for various satellite constellation combinations was analyzed based on 2014, and the navigation performance in 2020 was predicted based on the FOC plan of the satellite navigation system for each country. For this prediction, the orbital elements and nominal almanac data of satellite navigation systems that can be observed in the Korean Peninsula were organized, and the minimum elevation angle expecting signal shielding was established based on Matlab and the performance was predicted in terms of DOP. In the case of integrated navigation, a time offset determination algorithm needs to be considered in order to estimate the clock error between navigation systems, and it was analyzed using two kinds of methods: a satellite navigation message based estimation method and a receiver based method where a user directly performs estimation. This simulation is expected to be used as an index for the establishment of the minimum satellite constellation for obtaining the best navigation performance.

• 항공우주시스템공학회지
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• 제8권2호
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• pp.40-48
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• 2014

In this paper, a prototype of GPS jammer localization system for precise landing is developed. The jammer localization system consists of the four jamming signal receivers for collecting RF signal, one central tracking station for estimating jammer position, and one monitoring station for displaying estimated position on the map. In order to estimate jammer location TDOA and AOA algorithm are introduced, and the function and design parameters of the developed prototype are proposed. CW, DSSS, Swept CW jamming signals were generated and used. From the results, it can be confirmed that developed system meets the performance goal.

• Journal of Positioning, Navigation, and Timing
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• 제11권4호
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• pp.333-339
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• 2022

The satellite navigation system was developed for the purpose of calculating the location of local users, starting with the Global Positioning System (GPS) in the 1980s. Advanced countries in the space industry are operating Global Navigation Satellite System (GNSS) that covers the entire earth, such as GPS, GLONASS, Galileo, and BeiDou, by establishing satellite navigation systems for each country. Regional Navigation Satellite Systems (RNSS) such as QZSS and NavIC are also in operation. In the early 2010s, only GPS and GLONASS could calculate location using a single system for location determination. After 2016, the EU and China also completed the establishment of GNSS such as Galileo and BeiDou. As a result, satellite navigation users can benefit from improved availability of GNSS. In addition, before Galileo and BeiDou's Full Operational Capability (FOC) declaration, they used combined navigation algorithms to calculate the user's location by adding another satellite navigation system to the GPS satellites. Recently, it may be possible to calculate a user's location for each navigation system using the resources of a single system. In this paper, we evaluated the performance of single system navigation and combined navigation solutions of GPS, GLONASS, Galileo, BeiDou and QZSS individual navigation systems using high-performance GNSS receivers.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.108-115
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• 2012

현재까지 국내 위성항법 연구는 기존 위성항법체계기술을 활용한 연구가 주를 이루었으나, 새로운 위성항법 체계에 대한 연구도 점차 그 중요성이 부각되고 있다. 심지어 대한민국 독자적인 항법위성을 보유하자는 의견도 대두되었다. 지리적, 경제적, 기술적인 이유로 아직 수면 위로 떠오른 적은 없지만 자체 항법위성 관련 우주개발 로드맵이 제 1차 우주개발기본계획에 막연하게 제시되어 있다. 그러나 전세계적으로 4개의 전지국적 위성항법체계가 운영 중이거나 구축 중이고, 여러 개의 지역위성항법 시스템이 계획 중에 있다. 특히 아시아에서 중국은 독자의 전지구적 위성항법시스템 (COMPASS을 2020년에 완성하고자 위성을 발사 중에 있으며, 일본은 지역위성항법 시스템인 QZSS(Quasi Zenith Satellite System)를 2013년 완성을 목표로 제작 및 발사하고 있다. 이제 대한민국도 독자적인 위성항법시스템을 국내 우주개발 기술확보 및 항법안보를 위해서 꼭 개발해야 할 시기이다. 이 연구에서는 대한민국 자체의 위성항법시스템의 개발 여부나 그 개발 가능성을 논하지 않고, 다만 자체의 항법위성을 보유할 경우, 그 항법 메시지에 기존의 정보 외에 어떤 종류의 정보를 실을 수 있는지 조사하여 보았다. 대한민국의 지리적, 경제적 특성상 지역항법위성체계가 첫 번째 항법위성의 탑재체가 될 가능성이 높다. 따라서 이 연구도 이에 준해서 이루어졌다.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.335-342
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• 2023

Lunar Navigation Satellite System refers to a constellation of satellite providing PNT services on the moon. LNSS consists of main satellite and navigation satellites. Navigation satellites orbiting around the moon and a main satellite moves the area between the moon and the L2 point. The navigation satellite performs the same role as the Earth's GNSS satellite, and the main satellite communicates with the Earth for time synchronization. Due to the effect of the non-uniform shape of the moon, it is necessary to focus on the influence of the lunar gravitational field when designing the orbit simulation for navigation satellite. Since the main satellite is farther away from the moon than the navigation satellite, both the earth's gravity and the moon's gravity must be considered simultaneously when designing the orbit simulation for main satellite. Therefore, the main satellite orbit simulation must be designed through the three-body problem between the Earth, the moon, and the main satellite. In this paper, the orbit simulation tool for main satellite and navigation satellite required for LNSS was designed. The orbit simulation considers the environment characteristics of the moon. As a result of comparing long-term data (180 days) with the commercial program GMAT, it was confirmed that there was an error of about 1 m.

• Journal of Positioning, Navigation, and Timing
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• 제12권2호
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• pp.113-119
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• 2023

Satellite navigation systems, with the exception of the GLObal NAvigation Satellite System (GLONASS), adopt ionosphere models and provide ionospheric coefficients to single-frequency users via navigation messages to correct ionospheric delay, the main source of positioning errors. A Global Navigation Satellite System (GNSS) mostly has its own ionospheric models: the Klobuchar model for Global Positioning System (GPS), the NeQuick-G model for Galileo, and the BeiDou Global Ionospheric delay correction Model (BDGIM) for BeiDou satellite navigation System (BDS)-3. On the other hand, a Regional Navigation Satellite System (RNSS) such as the Quasi-Zenith Satellite System (QZSS) and BDS-2 uses the Klobuchar Model rather than developing a new model. QZSS provides its own coefficients that are customized for its service area while BDS-2 slightly modifies the Klobuchar model to improve accuracy in the Asia-Pacific region. In addition, BDS broadcasts multiple ionospheric parameters depending on the satellites, unlike other systems. In this paper, we analyzed the different ionospheric models of GPS, QZSS, and BDS in Korea. The ionospheric models of QZSS and BDS-2, which are based in Asia, reduced error by at least 25.6% compared to GPS. However, QZSS was less accurate than GPS during geomagnetic storms or at low latitude. The accuracy of the models according to the BDS satellite orbit was also analyzed. The BDS-2 ionospheric model showed an error reduction of more than 5.9% when using GEO coefficients, while in BDS-3, the difference between satellites was within 0.01 m.

• 전자통신동향분석
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• 제36권4호
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• pp.61-71
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• 2021

Navigation satellite systems (GPS, GLONASS etc.) provide three main services, i.e., positioning for location based services, navigation for multi-modal transportation services, and timing for communication and critical infrastructure services. They were started as military systems but were extended to civil service. Navigation satellite navigation system began with GPS in the USA and GLONASS in Russia at nearly the same time. Indian NavIC and Chines BDS announced their FOCs in 2016 and 2020, respectively and European Galileo and Japanese QZSS are catching up others. In these days, Navigation Satellite System, Positioning, Navigation, and Timing services are part of our daily life very closely. They are required for autonomous driving car, Unmanned vehicles like UAV, UGV, and UMV, 5G/6G telecommunications, world financial system, power system, survey, agriculture, and so on. The services among navigation satellite systems are very competitive and also cooperative one another. This article describes the status of these systems and evolution in the technical and service senses, which may be helpful for planning korea positioning system(KPS).

• International Journal of Aeronautical and Space Sciences
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• 제17권1호
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• pp.80-88
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• 2016

For next generation global navigation satellite systems, new carrier frequencies in Ku/V band are expected to emerge as a promising alternative to the current frequency windows in L band as they get severely congestive. In the case of higher frequency bands, signal attenuation phenomenon through the atmosphere is significantly different from the L band signal propagation. In this paper, a fundamental investigation is carried out to explore the Ku/V band as a candidate frequency band for a new global satellite navigation carrier signal, wherein specific attention is given to the effects of the dominant attenuation factors through the tropospheric propagation path. For a specific application, a candidate orbit preliminarily designed for the Korean regional satellite navigation system is adapted. Simulation results summarize that the Ku band can provide a promising satellite navigation implementation considering the present satellite's power budget, while the V band still requires technical advances in satellite transceiver system implementations.