• 한국항해항만학회지
• /
• 제34권2호
• /
• pp.97-103
• /
• 2010

It has been recognized that the risk from the vulnerability of GPS can lead to the extreme damage in the infrastructure of the civil and military in recent years. As an example, the intentional interference to GPS signal, named GPS jamming, was really performed to misguide GPS guided weapons during Iraq war in 2003, and the fact has also followed by the serious issues on GPS in civilian community. In the modernized military society, the navigation warfare(NAVWAR) based on the GPS jamming has been emerged and introduced as a military operation. The intentional interference to the future global navigation satellite system(GNSS) involving GPS must be also an important issue to civilian users in near future. This study is focused on the fundamental research prior to the research on "Potential principle of NAVWAR" under NAVWAR of the future warfare. In this paper, we would study on the investigation of NAVWAR based on electronic warfare(EW) and analyze characteristics of the jamming against GNSS's receivers. Then the general mechanism on GNSS jamming is proposed.

• Journal of Positioning, Navigation, and Timing
• /
• 제6권1호
• /
• pp.35-41
• /
• 2017

Precise Point Positioning (PPP) method is based on dual-frequency data of Global Navigation Satellite Systems (GNSS). The recent multi-constellations GNSS (multi-GNSS) enable us to bring great opportunities for enhanced precise positioning, navigation, and timing. In the paper, the multi-GNSS PPP with a combination of four systems (GPS, GLONASS, Galileo, and BeiDou) is analyzed to evaluate the improvement on positioning accuracy and convergence time. GNSS observations obtained from DAEJ reference station in South Korea are processed with both the multi-GNSS PPP and the GPS-only PPP. The performance of multi-GNSS PPP is not dramatically improved when compared to that of GPS only PPP. Its performance could be affected by the orbit errors of BeiDou geostationary satellites. However, multi-GNSS PPP can significantly improve the convergence speed of GPS-only PPP in terms of position accuracy.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2006년도 춘계학술발표회 논문집
• /
• pp.33-37
• /
• 2006

After USA removed the Selective Availability(SA), Global Positioning System(GPS) has monopolized tile world market and other countries have been depended on GPS, absolutely So the other countries, Russia, European Community(EC) and Japan, which apprehend to monopolize in technical and strategic parts, are developing the next generation GNSS including GLONASS Galileo and JRANS. And the countries are planning to provide the another GNSS. This research has focused on the next generation GNSS system based on GPS and Galileo system with developing a GNSS simulation software, named as GIMS2005, which generates and analyzes satellite constellation and measurements. Based on the software, a variety of simulation tests have been carried out to recognize limits of GPS-only system and potential benefits of integrated GPS/Galileo positioning In terms of satellite geometry strength and solution accuracy.

• 한국측량학회지
• /
• 제23권3호
• /
• pp.283-292
• /
• 2005

미국에서 GPS신호의 고의적 잡음을 해제한 후, GPS는 세계 시장을 독점하고 있으며 다른 나라에서는 GPS 사용에 있어 미국에 절대적으로 의존할 수 밖에 없게 되었다. 이에 기술적 전략적 종속을 우려한 러시아, EC 그리고 일본에서는 GLONASS, Galileo, JRANS의 차세대 GNSS 개발에 박차를 가하고 있다. 본 연구에서는 향후 제공될 유럽의 Galileo 위성의 영향을 사전에 분석하기 위해 GNSS 분석 소프트웨어인 GIMS2005를 개발하였으며 시뮬레이션에 기초한GPS/Gelileo 위성의 궤도, 가시위성수, 정밀도 저하율 그리고 측위기법별 정확도를 분석할 수 있었다 이를 통해 기존 GPS의 한계와 GPS/Galileo 결합의 잠재적인 이점을 도출할 수 있었다. 기하구조 분석에서는 GPS 단독과 비교하여 GPS/Galileo 결합의 경우 가시위성수는 205.50$\%$, 정밀도 저하율에서는 59.96$\%$ 향상됨을 보여준다. 이는 통합 시스템이 측위 정확도를 향상시킴을 의미한다.

• 한국산학기술학회논문지
• /
• 제14권1호
• /
• pp.94-100
• /
• 2013

본 연구에서는 VRS GNSS(GPS/GLONASS)를 이용하여 지적측량에서의 위치결정 정확도를 분석하여 보고, 이를 토대로 성과결정의 정확도 향상 가능성을 제시하고자 하였다. 연구결과 GPS 위성데이터만을 수신 한 결과 보다 GPS/GLONASS 위성데이터을 통합으로 수신해 위치를 결정한 결과가 대략 3cm 정도 위치정확도가 높은 것으로 분석되었다. 따라서 VRS GNSS 통합 수신 방식이 지적측량에 도입된다면 위치 정확도 향상을 기대할 수 있을 것으로 보인다.

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

• Journal of Positioning, Navigation, and Timing
• /
• 제7권3호
• /
• pp.175-181
• /
• 2018

The use of dual-frequency measurements from the Global Navigation Satellite System (GNSS) enables us to observe precise ionospheric total electron content (TEC). Currently, many GNSS reference stations in South Korea provide both GPS and GLONASS data. In the present study, we estimated the grid-based TEC values and relative receiver differential code biases (DCB) from a GNSS network operated by the Korea Astronomy and Space Science Institute. In addition, we compared the diurnal variations in a TEC time series from solutions of the GPS only, the GLONASS only, and combined GPS/GLONASS processing. A significant difference between the GPS only TEC and combined GPS/GLONASS TEC at a specific grid point over South Korea appeared near the solar terminator. It is noted that GLONASS measurements can contribute to observing a variation in ionospheric TEC over high latitude regions.

• 한국항해항만학회지
• /
• 제29권8호
• /
• pp.763-770
• /
• 2005

위성을 이용한 측위 시스템인 광역위성항법시스템(GNSS : Global Navigation Satellite System)은 측량 및 항법 등에 정확한 위치, 속도 그리고 시간 정보를 제공함으로써 위치결정의 중요한 도구가 되어왔다. 미 국방성에 의해 개발되어 운용되고 있는 범세계적위치결정시스템인 GPS는 GNSS 시장에 독점적인 존재이므로, GNSS 사용자는 GPS에 의존할 수 밖에 없는 상황이다. 이런 독점 상황을 극복하기 위하여 러시아, 유럽 그리고 일본은 독자적인 위성항법시스템을 개발하기 시작하였다. 특히 유럽의 Galileo 시스템은 2008년 발사 목표로 진행되고 있다. 본 연구는 위성궤도를 생성하고 분석할 수 있도록 제작한 GIMS2005 프로그램을 이용하여 차세대 GNSS인 Galileo 시스템을 GPS와 비교 분석함에 있다. 본 실험은 GPS 단독 처리의 한계와 GPS/Galileo 결합 시스템의 이점을 인식할 수 있게 한다. 기하구조 분석은 가시위성수, 정밀도 저하율, 내부 신뢰도 그리고 외부 신뢰도를 GPS 단독 처리와 비교하여 분석된다.

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

• 한국항행학회논문지
• /
• 제13권3호
• /
• pp.319-326
• /
• 2009

본 논문에서는 위성항법신호감시국용 GPS/갈릴레오 복합 수신기에서의 소프트웨어 기반의 GPS L1 및 갈릴레오 E1/E5a 신호처리 결과를 기술한다. 성능 검증을 위해 GNSS RF 신호 시뮬레이터 또는 GPS 위성의 실제 신호를 사용하였고, 세부적으로는 광대역 안테나, 112MHz 샘플링 주파수 및 8비트 양자화 레벨을 제공하는 RF/IF 유니트를 이용하여 갈릴레오 시험위성인 지오베-A(GIOVE-A) E1 신호처리를 통해, 갈릴레오 신호처리를 검증하고, FPGA 기반의 신호처리 보드상에서의 시험결과를 제시한다.