• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.418-426
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• 2022

Unlike OSR(observation space representation), the SSR(state space representation) augmentation system is suitable for a one-way broadcasting service because it provides the same corrections to all users in the service area. Due to this advantage, several GNSS(global navigation system) systems such as Galileo, BDS(beidou navigation satellite system), QZSS(quasi zenith satellite system) are establishing PPP (precise point positioning)/PPP-RTK precision positioning services based on SSR messages. Therefore, in this paper, we try to understand the trends of satellite-based PPP/PPP-RTK correction services by analyzing the system configurations, characteristics, and precise positioning performance of satellite-based SSR correction broadcasting services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7C
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• pp.608-615
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• 2007

Generally time of arrival (TOA) information via two way communications can be derived by accurate round trip time (RTT) between two devices. However, response time demanded in RTT measurement is long, a serious TOA error is caused by each different clock drift between two devices. In order to solve this problem, we propose the TOA and time difference of arrival (TDOA) estimation scheme with mitigating clock drift effect. To verify the performance of proposed method, we compared the proposed scheme with one way based TDOA acquisition method introduced by IEEE 802.15.4a Task Group and then we could conclude that the proposed method has better performance over other methods.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.107-108
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• 2014

As the demand for precise navigation has increased, more focus is put on the precise positioning, RTK(Real Time Kinematics) which has been used in the surveying field. The Position of Single Reference Station RTK or two-way network RTK such as VRS (Virtual Reference Station) is accurate enough to be used as a main technology in land surveying, however its service area and number of users is limited and the users are assumed static. This characteristic is not suitable to the navigation, whose service target is infinite number of users moving over a wide area. One-way network RTK has recently been suggested as a solution for the precise navigation technique for the mobile user. This paper shows the performance prediction of the one-way network RTK such as MAC(Master-Auxiliary Concept), or FKP (Flachenkorrekturparameter). To show the performance variation by the rover position, we constructed a simulation data of users on the grid with 0.1 degree spacing between 36.5 and 37 degree latitude and between 127 and 127.5 degree longitude.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1882-1883
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• 2007

본 논문은 근거리무선통신을 포함한 위치서비스를 위한 무선통신응용분야에 적용될 수 있는 고신뢰 고정밀 무선위치인식기술 방법을 제안한다. 제안된 위치인식방법은 양방향통신을 통해 추정된 무선태그의 신호세기 및 시간차를 측정된 거리정보를 바탕으로 상대적 위치에 대한 확률적 계산을 수행하게 되며, 측정데이터의 부정확성으로 인한 위치측정의 오차를 줄일 수 있다. 또한 제안된 고신뢰 무선측위 코아 스택을 근거리무선네트워크 형성이 가능한 2.4 GHz ISM 협대역 밴드의 ZigBee 무선비콘 및 무선태그 디바이스들에 탑재하고 실증시험을 위하여 스마트 홈 실내 환경 아래에서 $1m\;{\times}\;1m$ 의 위치인지를 가능케 하는 위치인식시스템을 구현한다.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.120-124
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• 2017

This paper describes the product of search and rescue system with dynamic model. This spread spectrum system based new standard of COSPAS-SARSAT is results of RF signal generation and transmission. we will test performance evaluation which implement signal process adapting Dynamic model and we will adapt the CAF model using TDOA and FDOA relationship.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1239-1242
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• 2005

텔레매틱스는 차량의 위치측위기술과 양방향 통신이 가능한 시스템을 이용하여 차량내 정보단말을 통해 차량과 운전자에게 다양한 정보 및 서비스를 제공하기 위한 종합적인 시스템을 의미한다. 다양한 서비스에 대한 요구가 점차 증가함에 따라, 다양한 첨단 기술들이 단말에 도입되고 있으며, 텔레매틱스 단말은 서버로부터 다양한 통신 수단을 통해 가동되어 전달되는 각종 서비스 정보 및 응용 소프트웨어를 사용자에게 제공하기 위한 실행 환경을 제공해야 한다. 이에, 본 논문에서는 AMI-C 기반의 텔레매틱스 단말용 응용 미들웨어를 제안하여, 공통적으로 단말이 제공해야 하는 서비스들을 제공하여 단말용 서비스 구축에 드는 시간과 비용을 줄이고자 한다.

• Journal of Navigation and Port Research
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• v.41 no.3
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• pp.87-92
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• 2017

To enhance the reliability and/or resilience of the PNT service included in the e-Navigation strategy of the IMO, the evaluation of the AIS-TWR method for the asynchronous R-mode for maritime service, which is available even in the absence of the GNSS, is described. For the AIS-TWR, which is capable of ranging through message exchange even without high precision synchronization, the operation scenario and the error factors according to the AIS system specifications are proposed and analyzed. Cramer-Rao Lower Bound is presented for the performance evaluation of the AIS-TWR algorithm. A simulation by AIS-TWR method of two AIS systems in a 3 km static environment shows estimation error of about 41m compared to the real value..

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_1
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• pp.463-469
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• 2013

In addition to the VRS-RTK service, FKP-RTK service launched recently in Korea however unlike VRS, it is not yet applied to various surveying tasks. VRS system is operated in two way communication over the mobile Internet. When user send rover position data to network RTK server and the server provides correction data to users continuously. It causes to increase communications load and makes delaying or failure in data transmission depends on server capacity and number of concurrent users. In contrast, since FKP system is one way communication system, user only receives correction data and area correction parameters for the selected Continuous Reference Station from the server. Thus, there is no limitation to the number of concurrent users in FKP system and it would be more efficient than VRS system in terms of economic. To this end, we performed FKP-RTK test for Unified Control Points and Urban Control Points where are located at 5 regions in Korea to evaluate the accuracy. As a result, almost of FKP positioning data are in error range of ${\pm}6.2cm$ in horizontal and it would be enough for construction survey such as for earth work in limited except precise structure survey.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.145-152
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• 2010

With the recent development of the ubiquitous computing technology, there are increasing interest and research in technologies such as sensors and RFID related to information recognition and location positioning in various ubiquitous fields. Especially, RTLS(Real-Time Locating Services) dealing with spatio-temporal data is emerging as a promising technology. For these reasons, the ISO/IEC published the RTLS standard specification for compatibility and interoperability in RTLS. Therefore, in this paper, we designed and implemented Spatio-temporal Query Processing Systems for efficiently managing and searching the incoming Spatio-temporal data stream of moving objects. Spatio-temporal Query Processing Systems's spatio-temporal middleware maintains interoperability among heterogeneous devices and guarantees data integrity in query processing through real time processing of unceasing spatio-temporal data streams and two way synchronization of spatio-temporal DBMSs. Web Server uses the SOAP(Simple Object Access Protocol) message between client and server for interoperability and translates client's SOAP message into CQL(Continuous Query Language) of the spatio-temporal middleware. Finally, this thesis proved the utility of the system by applying the spatio-temporal Query Processing Systems to a real-time Locating Services.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.229-236
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• 2009

UWB signal with high resolution capability can be used to estimate ranging and positioning in wireless personal area networks. The clock frequency differences of nodes have serious affects on asynchronous ranging methods to estimate locations of mobile nodes. The specification of high rate UWB describes successive TWR method with the estimation of a relative clock frequency offset. In this paper, we complete the ranging equations using relative frequency offset and time information, and propose a method to estimate the exact frequency offsets. We evaluate the ranging algorithms with simulation. The results show that the performances of the algorithms using frequency offsets are very close without noise. But, at noise environment, the method of exact frequency offsets shows better performance than that of relative frequency offsets.