• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.335-342
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• 2006

As PRC linear interpolation algorithm is applied after analysed and verified in this paper, the unknown location of a user can be identified by using PRC information of multi-DGPS reference station. The PRC information of each GPS satellite is not varying rapidly, which makes it possible to assume that PRC information of each GPS satellite varies linearly. So, the PRC regeneration algorithm with linear interpolation can be applied to improve the accuracy of finding a user's location by using the various PRC information obtained from multi-DGPS reference station. The desirable PRC is made by the linear combination with the known position of multi-DGPS reference station and PRC values of a satellite using signals from multi-DGPS reference station. The RTK-GPS result was used as the reference. To test the performance of the linearly interpolated PRC regeneration algorithm, multi-channel DGPS beacon receiver was built to get a user's position more exactly by using PRC data of maritime DGPS reference station in RTCM format. At the end of this paper, the result of the quantitative analysis of the developed navigation algorithm performance is presented.

• Spatial Information Research
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• v.18 no.5
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• pp.1-11
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• 2010

Since January 2009, Seoul Metro Government(SMG) is operating own Network RTK Systems connecting four(4) GNSS Reference Stations which are installed inside Seoul Metro City area. SMG is currently providing VRS data service via wireless internet for Network-RTK and RINEX data observed from GNSS Reference Stations. This paper will discuss utilization of data available from SMG Network-RTK System for various applications, and present the test results on practicalities of Virtual RINEX data. For the utilization of data available from SMG Network- RTK system, 1)NTRIP data delivery of GNSS realtime observables streaming and converting to RINEX at receiving side, 2) monitoring deformation of bulky structures using GNSS observation were discussed. In addition to those discussion, 3) broadcasting VRS correction data for job site via radio modem after acquiring such correction data on-line using NTRIP based GNSS Internet Radio from SMG Network-RTK System were introduced. For the test results on practicalities of Virtual RINEX data, 1) the post-processing results of the GNSS observation data on a certain point with GNSS Reference Station data have been compared to the post-processing results of Virtual RINEX data on the same point generated from SMG Network-RTK System, and 2) VRS RTK positioning results for a certain point and post-processing results of Virtual RINEX data for the point were compared. The results showed only a few mm difference, and the high possibility for using Virtual RINEX data for post-processing applications.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.8
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• pp.927-938
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• 2014

A number of crime and disease relief situation show a clear increasing trend in domestic and overseas country. In particular, we desperately need a fast location information sharing with high accuracy for dealing with this situation efficiently. In this paper, we propose a DGPS framework and performance evaluation based on Web service enable increase location accuracy using low-cost GPS or AGPS. The framework consists of mobile station to realize the final service by receiving the correction values that are created in the base station closest to the current position from DGPS server, base station system to transmit the correct values to DPGS server by installing at base point and DGPS framework working at DGPS server. Our framework is fundamentally designed to respond based on XML to service request. In addition, for performance evaluation, we make use of 3 sites of Level 2 city base-station among the base stations being operated in Suncheon-si. Through performance evaluation, we show that our framework outperforms about 10%~15% in terms of error improvement rate, compared with the existing schemes. And we have the advantage that various services can be expanded owing to receiving the correction values through mobile device such as, smart phone, smart pad, net-book by using XML based Web services.

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.429-436
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• 2019

The eLoran system is considered the best alternative because the vulnerability of satellite navigation systems cannot be resolved as perfect. Thus, South Korea is in the process of establishing a testbed of the eLoran system in the West Sea. To provide resilient navigation services to all waters, additional eLoran transmitters are required. However, it is difficult to establish eLoran transmitters because of various practical reasons. Instead, the positioning with NDGNSS/AIS source can expand the coverage and its algorithm with applying continuous waves is under development. Using the already operating NDGNSS reference station and the AIS base station, it is possible to operate the navigation system with higher accuracy than before. Thus, it is crucial to predict the performance when each system is integrated. In this paper, we have developed a simulation tool that can predict the performance of terrestrial integrated navigation system using the eLoran system, maritime NDGNSS station and the AIS station. The esitmated phase error of the received signal is calculated with the Cramer-Rao Lower Bound factoring the transmission power and the atmospheric noise according to the transmission frequency distributed by the ITU. Additionally, the simulation results are more accurate by estimating the annual mean atmospheric noise of the 300 kHz signal through the DGPS signal information collected from the maritime NDGNSS station. This approach can further increase the reliability of simulation results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.07a
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• pp.136-137
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• 2015

본 논문에서는 현재 운영 및 서비스 중인 DGNSS 기준국 및 감시국 서비스의 요구 성능과 그 한계에 대해 사용자 관점에서 분석하고, 이를 극복하기 위한 방안으로서 항만 항법신호(PNT) 감시 기술과 항법신호의 신뢰도를 결정하여 사용자에게 제공하기 위한 기술적 고려사항에 대해 분석한다. 먼저 DGNSS RSIM 운영 현황과 국제기구에서 요구하는 해양항법 요구성능에 대해 각각 분석한다. 다음으로 항만 혹은 사용자 관점에서 해당 요구성능을 충족시킬 수 있는지 분석한 다음, 이를 위한 보완할 수 있는 항만 항법신호 감시 및 신뢰도 서비스 기술에 대해 소개하고 향후 고려사항에 대해 제시한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.25-26
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• 2011

사용자 의사거리 보정 잔차(UDRE)는 위성항법보정정보의 측위성능을 예측하는데 이용하는 매우 중요한 무결성 감시정보이다. 위성항법보정정보 사용자는 위성별로 제공되는 사용자 의사거리 보정 잔차 정보를 이용하여 목표로 하는 측위성능을 보장할 수 있는지 여부를 계산하고, 이 결과를 반영하여 위성항법보강시스템의 보정정보를 사용할지 아니면, 무시할지를 판단한다. 즉, 사용자 의사거리 보정 잔차는 위성별로 제공되는 보정정보를 이용하여 보정을 한 후에도 제거되지 않고 남는 위성과 사용자 수신기 간의 통계학적 거리 오차로서 가우시안 분포를 갖는다고 본다. 따라서 동일한 위성항법신호 환경이라도 위성항법보강시스템의 종류와 응용분야별로 다르게 설정되는 측위성능의 보장 수준에 따라 사용자 의사거리 보정 잔차는 다른 값을 갖게 된다. 본 논문은 위성항법보강시스템의 무결성 감시성능에 영향을 미치는 사용자 의사거리 보정 잔차 추정기법의 성능해석을 목적으로 다중 기준국 원시정보를 이용한 사용자 의사거리 보정 잔차 추정기법 구조분석과 영향력을 소개하고, 성능에 영향을 미치는 인자와 사용자 의사거리 보정 잔차 추정성능의 지표에 대해 정의한다. 그리고 마지막으로 성능해석의 방법을 제안하고, 타당성을 검증한다.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.52-57
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• 2015

For the purpose of drawing out the technological criteria for the development of the National Environmental Satellite Center Earth Station, some constructional conditions for the establishment of the National Environmental Satellite Center and several characteristics of National Environmental Satellite Center Earth Station to be developed in the near future were analyzed. In addition, the structure of Environmental Satellite Earth Station and its internal interfaces by analyzing the characteristics of National Environmental Satellite Center Earth Station were depicted. In this paper, some top level requirements of the Environmental Satellite Earth Station and several interface requirements between the Environmental Satellite Earth Station and the Satellite Control Center were systematically described.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.509-514
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• 2007

The importance of the GPS is becoming larger and larger since it is one of the Global Navigation Satellite Systems and is regarded as a national infrastructure in the field positioning and timing Nowadays many researches avoiding and/or minimizing economic loss caused by unexpected fault of the GPS are being carried out because GPS fault can give a large impact on social security system as well as economic system NDGPS network which has been authorized by the Ministry of Marine and Fisheries provides services for marine users and evolved into a national infrastructure for GNSS users. Many researchers and engineers are doing research work in order to apply the NDGPS network to other fields. From this trend, it can be expected that the integrity and related functions for the NDGPS users will become more important than before. This paper analyzes integrity informations about the real GNSS fault and proposes method on integrity monitoring improvement of the DGPS reference station.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.550-557
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• 2017

Ionospheric delay, which affect the accuracy of GNSS positioning, is generated by electrons in Ionosphere. Solar activity level, region and time could make change of this delay level. Dual frequency receiver could effectively eliminate the delay using difference of refractive index between L1 to L2 frequency. But, Single frequency receiver have to use limited correction such as ionospheric model in standalone GNSS or PRC(pseudorange correction) in Differential GNSS. Generally, these corrections is effective in normal condition. but, they might be useless, when TEC(total electron content) extremely increase in local area. In this paper, monitoring algorithm is proposed for local ionospheric anomaly using multiple reference stations. For verification, the algorithm was performed with specific measurement data in Ionospheric storm day (20. Nov. 2003). this algorithm would detect local ionospheric anomaly and improve reliability of ionospheric corrections for standalone receiver.

• Journal of Advanced Navigation Technology
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• v.18 no.4
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• pp.260-267
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• 2014

For the purpose of improving the accuracy of Wide Area Differential GNSS (WA-DGNSS), estimation performance of ionospheric delay error which has a great impact on GPS error sources should be enhanced. This paper applied multi-constellation GNSS which represents GPS in USA, GLONASS in Russia, and Galileo in Europe to WA-DGNSS algorithm in order to improve performance of ionospheric delay estimation. Furthermore, we conducted simulation to analyze ionospheric delay estimation performance in Korean region by increasing the number of reference stations. Consequently, using multi-constellation GNSS to improve performance of ionospheric delay estimation is more effective than increasing the number of reference stations in spite of similar number of measurements which are in use for estimation. We expect this result can contribute to improvement for ionospheric delay estimation performance of single-frequency SBAS (Satellite Based Augmentation System) user.