중거리 기선 측지 성능 개선을 위한 지역 전리층 모델개발

다국어 초록 (Multilingual Abstract)

With the growth in civil and commercial applications, the Global Navigation Satellite System (GNSS) that provides the positioning, navigation, and timing information affects to our life. To meet all requirements for civilian users, particular efforts are being made in real time research to enhance positioning accuracy using GNSS. Real-time positioning techniques by GPS have been applied to several application fields such as geographic information system, location based service and intelligent transportation system with the key technology. Currently GPS do not guarantee the centimeter level of accuracy. In general high accuracy positioning service is limited to about 10 kilometer from the reference stations. The limitation of RTK (Real-Time Kinematic) is the distance between the reference station and rover due to distance dependent biases such as orbit error, atmospheric delay. The main reason for the limited range of RTK is the difficulty in estimating the atmospheric error biases and something factors. These biases can be estimated at the GPS network using either an undifferenced or double differenced approach. The basic concept of differential technique is to mitigate or reduce the common error sources, such as ionospheric and tropospheric delay, orbit error, satellite and receiver clock error so on. To achieve more accurate coordinates of positions, differential GPS technique is required, which allows even centimeter level accuracy in positioning using the so-called integer ambiguity resolution technique. For RTK-GPS applications, a key component is to resolve double differenced carrier phase ambiguity and computational speed is crucial. GPS integer ambiguity resolution is a key issue in high accuracy positioning. It was used a modified Least square AMBiguity Decorrelation Adjustment (MLAMBDA) method which can significantly reduce the computational complexity of the LAMBDA method. The MLAMBDA method improves the computational efficiency of both of the reduction and the search stage. In this paper, grid based ionospheric error correction values derived by the GPS network are applied to improve the positioning accuracy of the experimental sites. The test is easily anticipated from the known accuracy of short-baseline RTK positioning. For about 4.78km baseline, all of data processing types give very high availability of ambiguity-fixed positions, approximately L1~95.7%, L2~97.3%, Narrow-Lane(NL)~86.7%, Wide-Lane (WL)~99.9%, and Geometry-Free(GF)~92.6%. The mean error component of positioning with three-dimensional RMS (Root Mean Square) value was deviated by less than 3 centimeter from the true coordinate. For about 16.90km baseline, it was provided static positioning accuracy to centimeter level. When applying the regional ionospheric corrections, the positioning accuracy was improved about L1~24.9%, L2~20.0%, NL~9.1%, WL~4.6% and GF~7.2% on average in a static processing mode respectively. In case of 26.41km, 65.34km and 146.28km baselines, comparative testing and analysis were also conducted with respect to the positioning accuracy and ambiguity resolution success rate that is an important measure for the reliability of integer ambiguity resolution. All testing results also revealed improvement in the success rate of ambiguity resolution. The performance of the algorithm suggested in this paper can further contribute to improvement of the positioning accuracy.

목차 (Table of Contents)

• 제1장 서 론 1
• 1.1 연구배경 1
• 1.2 연구목적 3
• 1.3 연구개요 4
• 제2장 전리층 모델 6
• 2.1 Klobuchar 모델 8
• 2.2 전지구 전리층 모델 11
• 2.3 지역 전리층 모델 13
• 제3장 관측오차 모델 31
• 3.1 대류층 모델 31
• 3.2 Solid Earth Tide 모델 36
• 3.3 GPS 수신기 위상중심변화 모델 38
• 3.4 GPS 위성 위상중심변화 모델 41
• 3.5 Phase Wind Up 모델 45
• 3.6 Pole tide 모델 47
• 제4장 GPS 자료처리 48
• 4.1 관측값 48
• 4.2 차분기법 52
• 4.3 반송파 위상의 선형조합 56
• 4.4 DGPS 측위기법 63
• 4.5 실시간 이동측위(RTK) 기법 67
• 4.6 확장칼만필터(Extended Kalman Filter) 74
• 4.7 모호정수 결정방법 77
• 제5장 자료처리 결과 81
• 5.1 자료처리 방법 83
• 5.2 실험결과 및 분석 89
• 제6장 결 론 122
• 참고문헌 124
• ABSTRACT 128