• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.9
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• pp.1273-1280
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• 2014

This paper considers a GPS anti-spoofing problem. Spoofing is an intentional interference that mislead the GNSS receiver. The spoofing attack is very significant since the target receiver is not aware of being attacked from spoofing. Accelerometers can be used to detect the spoofing signal by being compared with the acceleration obtained from GPS information using Kalman filter. In this paper we propose an N by N-point average and M-point window algorithm to detect GPS spoofing by using accelerometers and GPS outputs. The performance of the proposed algorithm is analyzed using actual vehicle trajectory and spoofing trajectory generated from INS and GPS toolbox for simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.10
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• pp.928-935
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• 2000

In order to improve the performance of a GPS/DR integration system, the error sources of DR sensors should be modeled accurately, This results in the increases in the dimension of the integration filter and, consequently, computational load becomes large. To reduce the computational load, suggested in this paper is a decoupled GPS/DR integration scheme that consists of two cascaded Kalman filters. The GPS velocity output is used in the first filter to calibrate the DR sensor and to fix the velocity as well. The velocity from the first filter is fed to the second filter where the position is corrected using the GPS position output. Experimental results show that the proposed integration scheme has positioning performance comparable to the conventional coupled one, while its computation is reduced to about 2/3.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.54-54
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• 2000

For its synergistic relationship, an integrated SDINS/GPS system has been adopted in many navigation areas. As an application of SDINS/GPS integration, the in-flight alignment process of a SDINS utilizing GPS carrier phase measurements is introduced and analyzed via an observability analysis using nul1 space method. A measurement model of double-differenced GPS carrier phase measurements is newly derived in order to be used with a SDINS error model. Also, conditions for determining the complete observability of a SDINS/GPS system are suggested and proved. Consequently, it is shown that the system is not completely observable in case of one basel me. With one baseline aligned with y-axis of body frame, pitch error and x-axis accelerometer bias are unobservable states. Also shown is that al1 states are completely observable when sequential maneuver is performed. Above results are confirmed by a covariance analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.97-97
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• 2000

In this paper, a signal processing algorithm for software GPS receiver is proposed. The signal processor takes snapshot of the sampled If signal from the RF section of the GPS receiver. All the processing for code and carrier tracking and correlation are implemented using the digital signal processing techniques. In order to achieve fast code acquisition, correlation of the incoming GPS signal is performed using the FFT method, After code acquisition, to reduce the Doppler shift effect and increase the accuracy, the interpolation or the tracking are performed. The performance of the proposed processing algorithm is first evaluated using matlab/simulink. A signal acquisition board for sampling and logging GPS IF signal form the Mitel GPS RF chip set is constructed. In order to analyze the performance of the designed algorithm the experiments are performed and the results are analyzed.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.04a
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• pp.55-60
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• 2003

As the distance between GPS rover station and GPS base station increases, more decorrelated positioning errors limit the ability for PDGPS(Precise Differential GPS). The objective of this paper is to present the improvement of using VRS(virtual reference station) based on multiple GPS reference station network to single reference station for static positioning in post-processing mode. For this, the VRS observations from GPS observations of real reference stations are derived by using Web service in post-mode. The coordinates of check point post-processed by 27 kind of VRS observations compared with the known ones.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.65-71
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• 2004

The Development of GPS practical using and systematic fixing for GPS Quality Control System on On-Line. Developed the program that can prove GPS quality about GPS permanent observation stations or user GPS data in server client system environment of Web-Based objectively Developed Save-module of graph display of analysis result data and reporter form. Developed the program for making an estimate of GPS satellite information in server client system environment of Web-Based. Designed that the Display can be possible and store estimate result can expresses the form such as Sky Plot, DOPs, Satellite Elevation, satellite number cf predict-time and then the result can be preserved for report form.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.87-93
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• 2004

본 연구에서는 효율적인 GPS 데이터의 품질관리를 위한 GPS_QC 프로그램을 개발하여, GPS 데이터의 Quality 판단할 수 있는 총 8개의 Control 인자(위성의 배치, Multipath 오차량, 전리층 지연량 및 위성신호 강도 등)를 계산 할 수 있었으며, GPS 데이터 품질에 관련된 Control 인자의 결과값 및 허용오차 범위, 실제 관측데이터의 허용오차의 포함여부를 시계열 그래프와 보고서 형태로 제공하여 현장 등에서 간단하고 효율적으로 GPS 데이터의 품질관리를 가능하게 한다. 따라서 기존에 GPS 데이터 해석 후에나 판단이 가능했던 데이터의 품질을 현장이나 실내에서 직접 확인할 수 있게 함으로서 재측과 데이터 처리 시 소요되는 시간과 경비를 절감할 수 있을 것으로 판단된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.21 no.2
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• pp.123-129
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• 2003

This study analyzed and compared the results of baseline processing by Bernese GPS software packages and by GPSurvey software respectively. Then it investigated considerations when very long baselines are processed. There are rarely differences which is accompanied by baseline length when it is processed by Bernese GPS software but there are somewhat differences in proportion to the baseline length when it is processed by GPSurvey software.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.187-190
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• 2010

GPS survey came into wide use, but there are inefficient parts in related laws and regulations. Especially, to get GPS surveying results under 1.5cm permissible error the observation time must be longer than 8 hours in triangulation points surveying regulations. However, GPS surveying technology is developing now, so results could be acceptable under 4 hours observation time. Therefore, this study made a stable standard of observation time in GPS survey by comparing the errors due to observation time, and used PAJU, DOND and YANP's GPS data and 6 cadastral points' survey data. Also, to analyze the variations of results due to baseline distance, applied each GPS site as a fixed point and compared the positions. As a result, the stable satisfactory results were calculated under 4 hour survey, when the baseline distances were under 30km.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.7 no.1
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• pp.41-55
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• 1999

In case of KOREA, many difficulties are expected for pilots to adapt to the flight operational environment changes which we will meet suddenly in anytime of the future as the operating plan for GPS is not fully prepared yet. It is because GPS operation is rather difficult compared to other navigation equipments, and it takes much time and experience to be familiar with GPS instrument approach procedure. First of all, it is keenly required to establish GPS instrument approach procedure for the local airports to be familiar with GPS instrument approach procedure. We would like to introduce GPS instrument approach procedure for the Cheju International Airport as a basic model to help you to understand it.