• 한국항공운항학회지
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• 제14권1호
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• pp.55-62
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• 2006

Ionospheric signal delay is a critical factor for precision differential GNSS(Global Navigation Satellite Systems) applications such as GBAS(Ground-Based Augmentation System) and SBAS (Satellite-Based Augmentation System). Most concern is the impact of the ionospheric storm caused by the interaction between Solar and geomagnetic activities. After brief description of the ionosphere and ionospheric storm, ionospheric models for SBAS are discussed. History of recent ionospheric storms is reviewed and their impact on GNSS is discussed. In order to support Korean GNSS augmentation system development, a preliminary study on the regional ionosphere performed. A software tool for computing regional ionospheric maps is being developed, and initial results during a recent storm period is analyzed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 추계학술대회
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• pp.128-130
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• 2012

One of the hot issues on GNSS might be that China declared to broadcast the signal of the new Global Navigation Satellite System called Beidou-Compass in December 2011. The multi-GNSS systems with the existing GPS and GLONASS consist of more than 100 GNSS satellites and transmit their signals in near future. Many benefits are expected in accuracy, availability, integrity and increasing anti-jam performance. In this presentation, we have mainly investigated the latest issue for multi- GNSS and discussed spectrum analysis as well as the accuracy improvement issue. The use of the modern weapon system based on satellite navigation information was also briefly investigated in warfare.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.6-11
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• 2002

A term of GNSS(Global Navigation Satellite System) is widely used to represent a navigation method for global area using satellite in space orbit 1his system can provide accurate and continuous position, and timing sources synchronized to UTC. There are, however, certain disadvantage that system can not operate without line of sight environment to satellite, or system failure of either satellite or control station. It is the pseduolite technology for using indoor and also for back-up equipment of foreign system failure. Especially, ocean applications widely use the GNSS system for navigation, surveying, timing, and management of traffic, so, system failure of GNSS will be very critical problem to affect many aspects of ocean field. In this paper, we experimented the pseudolite technology for several application field to compare the result in different environment. We used the common CDGPS algorithm for in-door navigation and experimented in ocean engineering basin with metallic wall and gymnasiums with concrete wall. We also investigated the comparison result and considerations for ocean applications of pseudolite technology.

• 한국항행학회논문지
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• 제19권6호
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• pp.507-514
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• 2015

LX 한국국토정보공사 공간정보연구원에서는 2011년부터 LX 위성측위 (GNSS; global navigation satellite system) 네트워크를 구축하고 2014년부터 MAC (master-auxiliary correction) 방식의 네트워크 실시간 이동측위 (RTK; real-time kinematic) 전국망 운영 실험을 하고 있다. 본 연구에서는 LX GNSS 인프라의 구축 현황을 소개하고 LX GNSS RTK 서비스를 이용한 측위 성능 분석을 결과를 제시한다. 측위 성능 분석은 전북 전주, 서울, 그리고 인천에 설치된 지적도근점 중 총 25개를 이용하였으며, 1회 관측, 2회 중복관측, 그리고 5회 중복관측을 수행하였다. 측위 성능 비교를 위하여 한국국토정보공사 MAC과 국토지리정보원 VRS로 측량한 성과를 지적도근점의 고시좌표와 각각 비교하였다. 그 결과, 두 시스템이 평균오차와 표준편차가 1~2cm 수준으로 유사한 성능을 보였다.

• Journal of Positioning, Navigation, and Timing
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• 제8권2호
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• pp.79-85
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• 2019

The mission tasks of polar exploration utilizing unmanned systems such as glacier monitoring, ecosystem research, and inland exploration have been expanded. To facilitate unmanned exploration mission tasks, precise and robust navigation systems are required. However, limitations on the utilization of satellite navigation system are present due to satellite orbital characteristics at the polar region located in a high latitude. The orbital inclination of global positioning system (GPS), which was developed to be utilized in mid-latitude sites, was designed at $55^{\circ}$. This means that as the user is located in higher latitudes, the satellite visibility and vertical precision become worse. In addition, the use of satellite-based wide-area augmentation system (SBAS) is also limited in higher latitude regions than the maximum latitude of signal reception by stationary satellites, which is $70^{\circ}$. This study proposes a local-area augmentation system that additionally utilizes Global Navigation Satellite System (GLONASS) considering satellite navigation system environment in Polar Regions. The orbital inclination of GLONASS is $64.8^{\circ}$, which is suitable in order to ensure satellite visibility in high-latitude regions. In contrast, GLONASS has different system operation elements such as configuration elements of navigation message and update cycle and has a statistically different signal error level around 4 m, which is larger than that of GPS. Thus, such system characteristics must be taken into consideration to ensure data integrity and monitor GLONASS signal fault. This study took GLONASS system characteristics and performance into consideration to improve previously developed fault detection algorithm in the local-area augmentation system based on GPS. In addition, real GNSS observation data were acquired from the receivers installed at the Antarctic King Sejong Station to analyze positioning accuracy and calculate test statistics of the fault monitors. Finally, this study analyzed the satellite visibility of GPS/GLONASS-based local-area augmentation system in Polar Regions and conducted performance evaluations through simulations.

• Journal of Positioning, Navigation, and Timing
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• 제8권4호
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• pp.153-164
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• 2019

This paper presents the development of an end-to-end numerical simulator for signal design of the next generation global navigation satellite system (GNSS). The GNSS services are an essential element of modern human life, becoming a core part of national infra-structure. Several countries are developing or modernizing their own positioning and timing system as their demand, and South Korea is also planning to develop a Korean Positioning System (KPS) based on its own technology, with the aim of operation in 2034. The developed simulator consists of three main units such as a signal generator, a channel unit, and a receiver. The signal generator is constructed based on the actual navigation satellite payload model. For channels, a simple Gaussian channel and land mobile satellite (LMS) multipath channel environments are implemented. A software receiver approach based on a commercial GNSS receiver model is employed. Through the simulator proposed in this paper, it is possible to simulate the entire transceiver chain process from signal generation to receiver processing including channel effect. Finally, numerical simulation results for a simple example scenario is analyzed. The use of the numerical signal simulator in this paper will be ideally suited to design a new navigation signal for the upcoming KPS by reducing the research and development efforts, tremendously.

• Journal of Positioning, Navigation, and Timing
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• 제13권2호
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• pp.117-129
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• 2024

In this paper, we survey recent trends of International Global Navigation Satellite System (GNSS) organizations such as the International Committee on GNSS (ICG), International Civil Aviation Organization (ICAO), International Maritime Organization (IMO), and International Telecommunication Union (ITU), and investigate their impact on the maritime and aviation sectors. Each international organization promotes international cooperation, improvement of service quality, assurance of security, compliance with international regulations, and technological innovation and development. ICG develops a variety of satellite navigation enhancement systems. ICAO establishes international aviation regulations and standards to enhance aviation safety and security. IMO establishes international shipping conventions and rules to protect and regulate the shipping environment. Lastly, ITU establishes international communication regulations and standards. Investigation of such international organizations plays an important role in increasing the efficiency and reliability of GNSS systems. Each international organization promotes international cooperation, improvement of service quality, assurance of security, compliance with international regulations, and technological innovation and development. In the future, interoperability and compatibility with new satellite navigation systems and other GNSS and satellite navigation enhancement systems must be secured, so and thus investigation of international organizations must be conducted first.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.273-284
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• 2020

The performance of Global Navigation Satellite System (GNSS) chipset and Inertial Measurement Unit (IMU) sensors embedded in smartphones for location-based services (LBS) is limited due to the economic reasons for their mass production. Therefore, it is necessary to efficiently process the output data of the smartphone's embedded sensors in order to derive the optimum navigation values and, as a previous step, output performance of smartphone embedded sensors needs to be verified. This paper analyzes the navigation performance of such devices by processing the raw measurements data output from smartphones. For this, up-to-dated versions of smartphones provided by Samsung (Galaxy s10e) and Xiaomi (Mi 8) are used in the test experiment to compare their performances and characteristics. The GNSS and IMU data are extracted and saved by using an open market application software (Geo++ RINEX Logger & Mobile MATLAB), and then analyzed in post-processing manner. For GNSS chipset, data is extracted from static environments and verified the position, Carrier-to-Noise (C/N₀), Radio Frequency Interference (RFI) performance. For IMU sensor, the validity of navigation and various location-based-services is predicted by extracting, storing and analyzing data in static and dynamic environments.

• 한국전자통신학회논문지
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• 제18권3호
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• pp.545-554
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• 2023

현대 산업에서 위성항법시스템(Global Navigation Satellite System : GNSS)은 PNT 정보(측위(P : Positioning), 항법(N : Navigation), 시각동기(T : Timing))가 항상 제공되어야 하고, 그 정보를 기반으로 정밀한 위치추정이 요구되는 다양한 분야에 활용되고 있다. 특히, 2019년부터 시작된 COVID-19 펜데믹 상황에 대한 감염 예방 및 확산 방지를 위해 정밀한 위성항법시스템 기술과 이를 보조하는 다양한 기술들이 사용되어 왔고, 전 세계의 적극적인 방역과 감염 확산 억제 노력으로 엔데믹 상황으로의 전환을 앞두고 있다. 질병, E-health 분야는 감염병의 추적 및 감시와 더불어 원격 의료 서비스 제공을 위해 이용자의 위치정보가 반드시 필요한데, 위성항법시스템이 정확한 위치정보 제공에 주도적인 역할을 하고 있다. 본 논문은 이러한 위성항법시스템 기술이 질병 및 E-health 분야에 활용된 최신 연구 동향에 대해 조사한 결과를 제시하고 그 결과를 분석한다.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.349-358
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• 2023

The Satellite-Based Augmentation System (SBAS) plays a significant role in the fields of aviation and navigation: it corrects signal errors of the Global Navigation Satellite System (GNSS) and provides integrity information to facilitate precise positioning. These SBAS systems have been adopted as international standards by the International Civil Aviation Organization (ICAO). In recent SBAS system design, the Minimum Operational Performance Standards (MOPS) defined by the Radio Technical Commission for Aeronautics (RTCA) must be followed. In October 2014, South Korea embarked on the development of a Korean GPS precision position correction system, referred to as Korea Augmentation Satellite System (KASS). The goal is to achieve APV-1 Standard of Service Level (SoL) service level and acquisition of CAT-1 test operating technology. The first satellite of KASS, KASS Prototype 1, was successfully launched from the Guiana Space Centre in South America on June 23, 2020. In December 2022 and June 2023, the first and second service signals of KASS were broadcasted, and full-scale KASS correction signal broadcasting is scheduled to start at the end of 2023. The aim of this study is to analyze the precision of both the GNSS system and KASS system by comparing them. KASS is also compared with Japan's Multi-functional Satellite Augmentation System (MSAS), which is available in Korea. The final objective of this work is to validate the usefulness of KASS correction navigation in the South Korean operational environment.