• 대한전기학회논문지:시스템및제어부문D
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• 제55권6호
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• pp.286-295
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• 2006

This paper presents a design of a real-time software GPS receiver which runs on a PC. The software GPS receiver has advantages over conventional hardware based receivers in terms of flexibility and efficiency in application oriented system design and modification. In odor to reduce the processing time of the software operations in the receiver, a shared memory structure is used with a dynamic data control, and the byte-type IF data is processed through an Open Multi-Processing technique in the mixer and integrator which requires the most computational load. A high speed data acquisition device is used to capture the incoming high-rate IF signals. The FFT-IFFT correlation technique is used for initial acquisition and FLL assisted PLL is used for carrier tracking. All software modules are operated in sequence and are synchronized with pre-defined time scheduling. The performance of the designed software GPS receiver is evaluated by running it in real-time using the real GPS signals.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2005년도 GIS/RS 공동 춘계학술대회
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• pp.209-213
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• 2005

GPS를 이용한 측량 결과를 현장에서 직접 확인하여 적합성을 검토하는 것은 작업의 시간이나 효율성에서 많은 장점을 가지고 있다. 따라서 인터넷을 이용하여 사용자가 현장에서 GPS 측량 결과를 확인하고 성과를 점검할 수 있는 GPS 자료처리 웹 서비스의 구현이 필요하다. 인터넷을 이용한 GPS 자료처리의 웹 서비스는 GPS 자료를 인터넷을 이용하여 서버로 전송하는 사용자 부분(Client Part)과 전송된 GPS 자료를 처리하여 사용자에게 결과를 전송하는 서버 부분(Sever Part)으로 나된다. 본 연구에서는 업 로드 컴포넌트를 이용하여 GPS 자료를 업로드하고, 이 자료를 웹 브라우저와 연동된 자료처리 소프트웨어를 이용하여 처리하며, 처리된 결과를 사용자에 보여주는 소프트웨어를 개발하였다.

• 한국측량학회지
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• 제18권3호
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• pp.251-261
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• 2000

본 논문은 정밀한 기준좌표계인 ITRF96에 준거하여 GPS 측위를 수행하고 이에 따른 측위 정밀도를 분석하였으며, 여러 가지 방법에 따른 중, 장기선장의 데이터처리 결과를 제시하였다. 본 논문에서는 Jet Propulsion Laboratory에서 제공받은 정밀궤도력을 사용하여 GPS의 관측오차를 최소화하였으며, GIPSY-OASIS II 소프트웨어를 사용하여 관측기선의 비교 분석 결과를 제시하였다. 또한, 데이터 처리방법의 정확도를 검토하였다.

• Korean Journal of Geomatics
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• 제2권2호
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• pp.99-105
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• 2002

The accuracy of the Digital Photologging System, designed for the construction of the road Facility Database, highly depends on the positions and attitudes of the cameras from GPS/INS integration. In this paper, the development of a loosely coupled GPS/INS is presented. The performance of the system is verified through a simulation as well as a real test data processing. Since the IMU used in this study shows large systematic errors, the possible accuracy of the positions and attitudes of this low-performance IMU when combined with precise GPS positions are assigned. Currently, the integrated system shows the positional accuracy better than 5cm in real data processing. Although the accuracy of attitude based on real test could not be assigned at this time, it is expected that better than 0.5 degrees and 1.8 degrees for horizontal and down component are achievable according to the simulation result.

• 디지털산업정보학회논문지
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• 제10권2호
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• pp.61-73
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• 2014

An automatic vehicle location tracing system is to build GIS server and on transmission for providing service in various ways by collecting a GPS location information from each vehicle. It is to save GPS data from OBU built-in on the vehicle and transmit the GPS data using the RSU on the roadside and WAVE communication technology. The collected data from the RSU is transmitted to the GIS server and stored in DB(database) and based on the GPS data that was collected from the each vehicle the system is to provide user service to suit the applications so it is to provide various services between RSU and OBU. In this paper, by implementing a multi-session process between the RM and the RMA a variety of services between RSU and OBU are provided. In addition, the system is designed and implemented using GPS to provide a variety of services, for the services provided from each RMA by configuring them as an independent session so it enables a variety of services implemented from one of RSU. With the result of the comparative analysis on the multi-session processing and single-session processing it shows that the differenes of them are minor in repect of the data loss rate and the data transfer rate but various services can be provided.

• 제어로봇시스템학회논문지
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• 제12권8호
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• pp.752-758
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• 2006

A GPS receiver provides much information such as calculated position, speed, heading, status of satellites, current time errors, etc. It is well-known that GPS signals from GPS receiver mounted on moving vehicle are often distorted, contaminated by various noises, and blocked by tunnel or tall buildings. The phenomenon often obstructs correct navigation especially when a vehicle keeps stopping or is moving in low speed. Therefore it is needed to pre-process the signals to adapt it to various applications. In this paper, an algorithm to pre-process the signals is proposed. For this, GPS data obtaining from uNAV GPS receiver are analyzed and classified based on dynamic characteristic. Then, the proposed algorithm is applied to the data and some test results are shown to verify the usefulness of the algorithm.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.178-181
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• 2005

The positioning accuracy of the Global Positioning System (GPS) has been improved considerably during the past two decades. The main error sources such as ionospheric refraction, orbital uncertainty, antenna phase center variation, signal multipath, and tropospheric delay have been reduced substantially, if not eliminated. In this study, the GPS data collected by the GPS receivers that were established as continuously operating reference stations by International GNSS Service (IGS), Ministry of the Interior (MOl), Central Weather Bureau (CWB), and Industrial Technology Research Institute (ITRI) Of Taiwan are utilized to investigate the impact of atmospheric water vapor on GPS positioning determination. The surface meteorological measurements that were concurrently acquired by instruments co-located with the GPS receivers include temperature, pressure and humidity data. To obtain the influence of the GPS height on the proposed impact study. A hydrodynamic ocean tide model (GOTOO.2 model) and solid earth tide were used to improve the GPS height. The surface meteorological data (pressure, temperature and humidity) were introduced to the data processing with 24 troposphere parameters. The results from the studies associated with different GPS height were compared for the cases with and without a priori knowledge of surface meteorological measurements. The finding based on the measurements in 2003 is that the surface meteorological measurements have an impact on the GPS height. The associated daily maximum of the differences is 1.07 cm for the KDNM station. The impact is reduced due to smoothing when the average of the GPS height for the whole year is considered.

• 한국항행학회논문지
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• 제13권3호
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• pp.319-326
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• 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.

• 한국측량학회지
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• 제24권1호
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• pp.9-18
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• 2006

본 연구는 GPS 데이터 해석 시 정밀도를 높이고 현장에서 관측시간 내 GPS 측량의 적절성 및 재측 여부 등을 직접 결정할 수 있도록 GPS 데이터 품질관리 프로그램을 개발하는 것에 그 목적이 있다. 본 연구에서 개발된 GPS_QC 프로그램은 관측시간 내 위성의 기하학적 배치(DOP)와 다중경로 오차량, 전리층 지연량 및 사이클 슬립 등의 품질관리 인자(quality control parameters)를 RINEX 형식의 GPS 관측데이터로부터 직접 계산이 가능하도록 설계되었으며, 이러한 품질관리 인자는 시계열 형태와 그래프로 제공된다. GPS_QC 프로그램은 일반 사용자들이 다루기 어려웠던 기존의 복잡한 GPS 데이터 품질 확인을 간편하게 수행할 수 있도록 함으로써 실제 현장에서 잘못된 GPS 관측에 따른 재측여부 등을 직접 결정할 수 있게 함으로써 시간적 경제적 손실을 절감시키고, GPS 위치해석 시 정밀도를 높일 수 있을 것으로 판단된다.

• International Journal of Aeronautical and Space Sciences
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• 제1권2호
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• pp.43-49
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• 2000

The Global Positioning System (GPS) is becoming more attractive navigation means for LEO (Low Earth Orbit) spacecraft due to the data accuracy and convenience for utilization. The anomalies such as serious variations of Dilution-Of-Precision (DOP), loss of infrequent 3-dimensional position fix, and deterioration of instantaneous accuracy of position and velocity data could be observed, which have not been appeared during the ground testing. It may cause lots of difficulty for the processing of the orbit control algorithm using the GPS data. In this paper, the characteristics of the GPS data were analyzed according to the configuration of GPS receiver such as position fix algorithm and mask angle using GPS navigation data obtained from the first Korea Multi-Purpose Satellite (KOMPSAT). The problem in orbit tracking using GPS data, including the infrequent deterioration of the accuracy, and an efficient algorithm for its countermeasures has also been introduced. The reliability and efficiency of the modified algorithm were verified by analyzing the effect of the results between algorithm simulation using KOMPSAT flight data and ground simulator.