• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.353-361
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• 2021

This paper presents the jamming effect on the L5 band of Global Navigation Satellite System (GNSS) by analyzing real data collected via measurement campaigns in Korea region. In fact, the L5 band is one of the dedicated bands for various satellite navigation systems such as Global Positioning System (GPS), Galileo, BeiDou (BDS), and Quasi Zenith Satellite System (QZSS). And this band is also allocated along with various systems used for aeronautical radio navigation systems (ARNS). Among ARNS, the Distance Measuring Equipment (DME) and the Tactical Air Navigation System (TACAN) are systems that transmit and receive strong power pulse signals, which may cause unintentional jamming in the reception of GNSS signals. In this paper, signals in the main lobe of GPS L5, Galileo E5a, BDS B2a, and QZSS L5 are collected in Korean region to confirm whether the jamming effect exists in the band. And then, the pulse blanking technique, which is a simple signal processing technique capable of responding to pulsed jamming, is applied to analyze the jamming effect of DME/TACAN on the L5 band.

• Journal of Positioning, Navigation, and Timing
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• 제13권1호
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• pp.1-13
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• 2024

In this paper, we investigate the signal design of six (USA, EU, Russia, China, Japan, and India) countries for Global Navigation Satellite Systems (GNSS). Recently, a navigation satellite system that is capable of high-precision and reliable Positioning, Navigation, Timing (PNT) services has been developed. Prior to system design, a survey of the signal design for other GNSS systems should precede to ensure compatibility and interoperability with other GNSS. The signal design includes carrier frequency, Pseudorandom Noise (PRN) code, modulation, navigation service, etc. Specifically, GNSS is allocated L1, L2, and L5 bands, with recent additions of the L6 and S bands. GNSS uses PRN code (such as Gold, Weil, etc) to distinguish satellites that transmit signals simultaneously on the same frequency band. For modulation, both Binary Phase Shift Keying (BPSK) and Binary Offset Carrier (BOC) have been widely used to avoid collision in the frequency spectrum, and alternating BOCs are adopted to distinguish pilot and data components. Through the survey of other GNSS' signal designs, we provide insights for guiding the design of new satellite navigation systems.

• Journal of Positioning, Navigation, and Timing
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• 제6권4호
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• pp.205-210
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• 2017

Multi-Global Navigation Satellite System (GNSS) can significantly improve the positioning accuracy and convergence speed. The reliability and availability of multi-GNSS precise point positioning (PPP) is steadily increasing with the rapid development of GNSS satellites. In this study, multi-GNSS PPP analysis is performed to compare the positioning precision by processing the observations from different GNSS systems (GPS, GLONASS, Galileo and BeiDou). To improve the positioning performance of the multi-GNSS PPP, we employed the weighed measurement noise (WMN) method. After applying WMN method to multi-GNSS PPP, positioning precision is improved by approximately 26.3% compared to the GPS only solutions, and by approximately 9.1% compared to combined GPS, GLONASS, and Galileo PPP.

• 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.

• 한국항행학회논문지
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• 제20권1호
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• pp.37-44
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• 2016

한국은 성능기반항행 (PBN; performance-based navigation)으로 전환하기 위한 단계적 PBN 이행계획을 2010년에 수립하고 로드맵에 따른 새로운 비행절차를 개발 중에 있다. PBN 비행절차에는 GNSS (global navigation satellite systems), DME (distance measuring equipment), VOR (VHF omnidirectional range), INS (inertial navigation system) 등의 항행시설 (NAVAID; navigation aid)이 활용되는 것으로 되어있다. 그 중에서 GNSS를 이용한 PBN 업무제공이 중심을 이루고 있는 실정이다. 그러나 위성항법신호의 인위적, 자연적 간섭에 의한 취약성이 발견됨에 따라 세계 각국은 다양한 대안항법(APNT; alternative positioning, navigation and timing) 기술을 연구하고 있다. 본 논문에서는 GNSS 신호가 가용하지 않을 경우 기존의 항행시스템으로 지속적인 PBN 운항이 가능한지를 분석하였으며, 결과적으로 국내 일부 공항은 접근 단계 구역에서 대안항법의 구축이 필요한 것으로 나타났다.

• 전자통신동향분석
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• 제38권2호
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• pp.12-25
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• 2023

Positioning, navigation, and timing information has become a key element in the national core infrastructure and for emerging technologies, such as autonomous driving, lunar exploration, financial systems, and drones. Therefore, the provision of that information by navigation satellite systems is becoming increasingly important. Existing systems such as GPS (Global Positioning System), GLONASS (GLObal NAvigation Satellite System), and BDS (BeiDou Navigation Satellite System) also provide augmentation, safety-of-life, search & rescue and short message communication and authentication services to increase their competitiveness. Those services and the signals generated for their provision have their own purpose and requirements. This article presents an overview of existing or planned satellite navigation satellite system services and signals, aiming to help understand their current status.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.14-19
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• 2020

본 논문은 차등 위성항법 보정 시스템을 이용한 측위 오차 보정을 통해 소형 드론의 위치를 정밀하게 계측할 수 있는 시스템 구현에 대해 서술하고 있다. 본 시스템은 고정된 위치에 자리하는 기준국과 실시간으로 움직이는 이동국(드론)으로 이루어져 있다. 자체 기준국 위치 정보와 국가에서 제공하는 관측 정보를 함께 후처리하여 기준국의 정밀 좌표를 획득하는 과정에 대해 서술하고, 이동국을 정밀 추적하기 위한 차등 위성 항법 시스템의 하드웨어 및 소프트웨어 구성에 대해 설명한다. 기준국 및 이동국 구현에 있어 저가의 경량 위성 항법 수신기 및 오픈소스 소프트웨어 코드와 라이브러리를 활용하여 범용성과 경제성을 극대화 하였으며, 오차 보정 정보 송수신에는 비 면허 주파수 대역 무선통신인 지그비(Zigbee)를 사용하였다. 본 시스템을 이용하여 소형 드론 위치 추적 시험 결과, 평균 측위 오차가 0.8m 및 최대 측위 오차가 1.2m로, 단일 위성 항법 수신기를 사용했을 경우 대비 오차가 86% 개선됨을 확인할 수 있었다.

• 정보통신설비학회논문지
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• 제9권3호
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• pp.92-101
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• 2010

Energy efficiency and safe mobility are the two key constituents of the future automobile. The technologies that enable these features are now heavily dependent upon information and communication technology rather than traditional auto-mechanical technology. This paper presents an exploratory project 'Smart&Green Vehicle Project' at Western Michigan University which is to improve the geographical location accuracy of vehicles and to study various applications of making such location data available. Global Positioning System (GPS), Inertial Navigation System (INS), Vehicular Ad-hoc Network (VANET) technology, and data fusion among these technologies are investigated. Testing and evaluation is done on systems which will gather vehicular positioning data during GPS signal loss. Vehicles in urban settings do not acquire accurate positioning data from GPS alone; therefore there is a need for exploration into technology that can assist GPS in urban settings. The goal of this project is to improve the accuracy of positioning data during a loss of GPS signal. Controlled experiments are performed to gather data which aided in assessing the feasibility of these technologies for use in vehicular platforms.

• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.952-959
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• 2016

This paper proposes a novel indoor positioning system (IPS) that uses a calibrated camera sensor network and dense 3D map information. The proposed IPS information is obtained by generating a bird's-eye image from multiple camera images; thus, our proposed IPS can provide accurate position information when objects (e.g., the mobile robot or pedestrians) are detected from multiple camera views. We evaluate the proposed IPS in a real environment with moving objects in a wireless camera sensor network. The results demonstrate that the proposed IPS can provide accurate position information for moving objects. This can improve the localization performance for mobile robot operation.

• 제어로봇시스템학회논문지
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• 제4권2호
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• pp.220-225
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• 1998

In GPS (Global Positioning System) positioning, various measures can be used to select satellites or to evaluate the positioning results. Among these, GDOP (Geometric Dilution of Precision) and RGDOP (Relative GDOP) are the most frequently used. Although these measures are frequently used, the relationship between them is not clearly known. Moreover, the condition number is used as a traditional measure of numerical stability in solving linear equations. Sometimes, the volume of a tetrahedon made by the line of sight vector is used for simplicity. All of these measures share some common properties as well as differences. The relationships between these measures are analyzed in this paper.