• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.27-31
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• 2006

With the fast developing pace, the Galileo system is entering the navigation stage with high profile. At the same time, U.S. is accelerating his GPS modernization schedule, and Russian also begins to resuscitate their GLONASS. Moreover, Chinese Beidou system has also joined the satellite navigation family with low profile already. And of course Japanese QZSS even moves forward. Along with the bitter competition in technology, finance, market and even military affairs, all these systems will firmly benefit each other and massively extend the role of civil satellite navigation industry in the future. The Global Navigation Satellite Systems (GNSS) would be almost certain to include above major satellite navigation systems. Thus how to utilize the navigation satellite resource for world peace and promote the progress of mankind should be the key issue of this century.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.9-14
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• 2014

Recently, precision guided munition systems and missile defense systems based on GPS have been taking a key role in modern warfare. In warfare however, unexpected interferences cause by large/small scale fading, radio frequency interferences, etc. These interferences result in a severe GPS positioning error, which could occur late supports and friendly fires. To solve the problems, this paper proposes an interference mitigation positioning method by adopting a wavelet denoising filter algorithm. The algorithm is applied to a GPS/QZSS/Wi-Fi combined positioning system which was performed by this laboratory. Experimental results of this paper are based on a real field test data of a GPS/QZSS/Wi-Fi combined positioning system and a simulation data of a wavelet denoising filter algorithm. At the end, the simulation result demonstrates its superiority by showing a 21.6% improved result in comparison to a conventional GPS system.

• Information and Communications Magazine
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• v.28 no.7
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• pp.25-36
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• 2011

본고에서는 대표적인 GNSS 인 미국의 GPS와 그 한계성능을 언급하고, 이를 극복하기 위한 GPS 현대화 과정을 소개한다. 이와 함께 차세대 GNSS인 러시아의 현대화된 GLONASS, 유럽연합의 Galileo 시스템, 중국의 COMPASS, 일본의 JRANS-QZSS 개발현황을 정리한다.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.4
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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.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.471-474
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• 2009

A Hanbitho, which is a ship to measure maritime transportation system, observes and estimates the maritime transportation system and its signal to be able to receive in our closed sea New GNSS systems are constructed such as GLONASS, GALILEO, QZSS, however, our ships can use SBAS service such as MSAS of Japan. So, it is needed to reconstruct new measuring system to observe and estimate new GNSS and SBAS. In this paper, we propose the upgrade method of Hanbiho measuring system.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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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 the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.231-238
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• 2007

This paper describes the availability of the forthcoming integrated GNSS(Global Navigation Positioning System) positioning that includes GPS(Global Positioning System), Galileo, and QZSS(Quasi-Zenith Satellites System). We built a signal propagation model that identifies direct, multipath, and diffraction signals, using the principles of specular reflection and ray tracing technique. The signal propagation model was combined with 3D GIS(three-dimensional geographic information system) in order to measure the satellite visibility and positioning error factors, such as the number of visible satellites, average elevation of visible satellites, optimized DOP(dilution of position) values, and the portion of multipath-producing satellites. Since Galileo and QZSS will not be fully operational until 2010, we used a simulation in comparing GPS and GNSS positioning for a $1km{\times}1km$ developed area in Shinjuku, Tokyo. To account for local terrain variation. we divided the target area into 40,000 $5m{\times}5m$ grid cells. The number of visible satellites and that of multipath-free satellites will be greatly increased in the integrated GNSS environment while the average elevation of visible satellites will be higher in the GPS positioning. Much decreased PDOP(position dilution of precision) values indicate the appropriate satellite/user geometry of the integrated GNSS; however, in dense urban areas, multipath mitigation will be more important than the satellite/user geometry. Thus, the efforts for applying current technologies of multipath mitigation to the future GNSS environment will be necessary.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.58-63
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• 2015

Due to GPS signal's vulnerability of jamming attack, various enhancement techniques are needed. Among variety of techniques, we focused on GPS receiver's anti-jamming techniques. There are many anti-jamming methods at GPS receivers which include filtering methods in time domain, frequency domain and space domain. However, these methods are ineffective to signals, which include both jamming and noise. To solve the problem, this paper proposes a jamming separation scheme by using a BSS method in a jamming environment. As separated GPS signals include noise after the jamming separation method, it is difficult to receive accurate GPS signals. For this reason, this paper also proposes a wavelet de-noising method to effectively eliminate noise. Experimental results of this paper are based on a real field test data of an integrated GPS/QZSS/Wi-Fi positioning system. At the end, the simulation result demonstrates its superiority by showing improved positioning accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2285-2291
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• 2015

At present, available positioning satellites are not only the GPS, but also GLONASS, GALILEO, QZSS, BeiDou. However, the differential GPS, the augmentation service for increase the positioning accuracy, is follow the RTCM version 2.3 standard. So, it can service the correction information about only GPS. For solve this problem, RTCM is making the new version of RTCM message standard that can service the correction information for all of available GNSS. In South Korea, the software DGNSS RSIM system was installed at almost the whole DGNSS reference station. In this reason, that can cope with the new RTCM version 2.4 quickly. However, the DGNSS Reference Station based RSIM 1.3 can not make the GNSS's PRC simultaneously and can not support RTCM version 2.4. Thus, in this paper, the version of RTCM 2.4 is analyzed and the RTCM version 2.4 message generating module's architecture for software DGNSS reference station is designed.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.286-290
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• 2011

LBS(Location Based System) is the essential technology of ubiquitous market and utilizes the GNSS(Global Navigation Satellite). GNSS includes GPS of USA, Galileo of Europe Union, QZSS of Japan, Compass of China, and IRNSS of India. Related researches have recently been conducted. Once the satellite is launched, the maintenance such as modification and verification of its function is difficult. Therefore, before the launch of satellites, more precise and concrete verification of performance and operations are needed. In order to do this, hardware testbed may be developed. but software simulators can provide more flexible and cost effective simulation results. These simulators should provide the essential function handling all kinds of error features experienced upon propagation of the GNSS signal. In this paper, we present a design and implementation results of a window-based simulator applying the modeling of various error features for several GNSS.