With the appearance of China's BeiDou system and EU's Galileo system and the restoration and improvement of Russia's GLONASS navigation system, the single GPS navigation satellite system has been gradually developed into multi-GNSS (multi-constellation global navigation satellite systems). Multi-GNSS with precise positioning will become the development trend of GNSS precise positioning in the future. Using the observation data collected by PPP (precise point positioning), which integrates the four major satellite navigation systems of GPS、 GLONASS、 BeiDou and Galileo, this paper conducts a preliminary study and analyzes the positioning performance of multi-system PPP. According to the experiment, in areas where single system observation geometrical configuration is unsatisfactory, multi-system integration can greatly improve the positioning accuracy and convergence rate of PPP. The convergence rate of multi-constellation PPP is 30% to 50% higher than that of single GPS, and the positioning accuracy can also be improved 10% to 30%, especially in terms of elevation direction. Besides, under observation circumstance where the end elevation angle of satellite is larger than 30 degrees, single GPS fails to carry out continuous positioning due to lack of visible satellites, while multi-constellation PPP can still get positioning results, with relatively high accuracy in horizontal direction especially.
[1] GAO Yang, SHEN Xiaobing.Improving Ambiguity Convergence in Carrier Phase-based Precise Point Positioning[C]//Proceedings of the 14th International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GPS2001). Salt Lake City:Salt Palace Convention Center, 2001:1532-1539.
[2] CHEN Wu, HU Congwei, LI Zhihua, et al. Kinematic GPS Precise Point Positioning for Sea Level Monitoring with GPS Buoy[J]. Journal of Global Positioning Systems, 2004, 3(1-2): 302-307.
[3] ZHANG Xiaohong, ANDERSEN O B. Surface Ice Flow Velocity and Tide Retrieval of the Amery Ice Shelf Using Precise Point Positioning[J]. Journal of Geodesy, 2006, 80(4): 171-176.
[4] BISNATH S, GAO Yang. Current State of Precise Point Positioning and Future Prospects and Limitations[M]//SIDERIS M G.Observing Our Changing Earth. Berlin: Springer, 2007, 133: 615-623.
[5] ZHANG Xiaohong, LIU Jingnan, FORSBERG R. Application of Precise Point Positioning in Airborne Survey[J]. Geomatics and Information Science of Wuhan University, 2006, 31(1): 19-22, 46. (张小红, 刘经南, FORSBERG R. 基于精密单点定位技术的航空测量应用实践[J]. 武汉大学学报: 信息科学版, 2006, 31(1): 19-22, 46.)
[6] YUAN Xiuxiao, FU Jianhong, LOU Yidong. GPS-supported Aerotriangulation Based on GPS Precise Point Positioning[J]. Acta Geodaetica et Cartographica Sinica, 2007, 36(3): 251-255. (袁修孝, 付建红, 楼益栋. 基于精密单点定位技术的GPS辅助空中三角测量[J]. 测绘学报, 2007, 36(3): 251-255.)
[7] ZHANG Baocheng, OU Jikun, YUAN Yunbin, et al. Precise Point Positioning Algorithm Based on Original Dual-frequency GPS Code and Carrier-phase Observations and Its Application[J]. Acta Geodaetica et Cartographica Sinica, 2010, 39(5): 478-483. (张宝成, 欧吉坤, 袁运斌, 等. 基于GPS双频原始观测值的精密单点定位算法及应用[J]. 测绘学报, 2010, 39(5): 478-483.)
[8] ZHANG Xiaohong, HE Xiyang, LI Xingxing. Analysis of Undifferenced Kinematic POD for LEOs Using Trip[J]. Geomatics and Information Science of Wuhan University, 2010, 35(11): 1327-1330. (张小红, 何锡扬, 李星星. Trip软件非差几何法精密定轨精度分析[J]. 武汉大学学报: 信息科学版, 2010, 35(11): 1327-1330.)
[9] ZHANG Baocheng, OU Jikun, YUAN Yunbin, et al. Calibration of Slant Total Electron Content and Satellite-receiver's Differential Code Biases with Uncombined Precise Point Positioning Technique[J]. Acta Geodaetica et Cartographica Sinica, 2011, 40(4): 447-453. (张宝成, 欧吉坤, 袁运斌, 等. 利用非组合精密单点定位技术确定斜向电离层总电子含量和站星差分码偏差[J]. 测绘学报, 2011, 40(4): 447-453.)
[10] SHI Chuang, ZHAO Qile, LI Min, et al. Precise Orbit Determination of BeiDou Satellites with Precise Positioning[J]. Science China Earth Sciences, 2012, 55(7): 1079-1086. (施闯, 赵齐乐, 李敏, 等. 北斗卫星导航系统的精密定轨与定位研究[J]. 中国科学: 地球科学, 2012, 42(6): 854-861.)
[11] MONTENBRUCK O, STEIGENBERGER P, KHACHIKYAN R,et al. IGS-MGEX: Preparing the Ground for Multi-constellation GNSS Science[J]. Inside GNSS, 2014, 9:42-49.
[12] PÍRIZ R, CALLE D, MOZO P,et al.Orbits and Clocks for GLONASS Precise-point-positioning[C]//Proceedings of the 22nd International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS 2009). Savannah:Savannah International Convention Center, 2009: 2415-2424.
[13] MELGARD T, VIGEN E, DE JONG K, et al.G2: the First Real-time GPS and GLONASS Precise Orbit and Clock Service[C]//Proceedings of the 22nd International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS 2009). Savannah: Savannah International Convention Center, 2009: 1885-1891.
[14] MELGARD T, VIGENE, ØRPEN O, et al. Pulling in All Signals PPP with GPS and GLONASS: The New G2[J]. GPS World, 2010, 21(3): 28.
[15] DACH R, LUTZS,MEINDLM, et al. Combining the Observations from Different GNSS[C]//EUREF 2010 Symposium. Gävle:Bundesamtfür Kartographie und Geodäsie,2010.
[16] ZHANG Xiaohong, GUO Fei, LI Xingxing, et al. Study onPrecise Point Positioning Based on Combined GPS and GLONASS[J]. Geomatics and Information Science of Wuhan University,2010, 35(1): 9-12. (张小红, 郭斐, 李星星, 等. GPS/GLONASS组合精密单点定位研究[J]. 武汉大学学报: 信息科学版,2010, 35(1): 9-12)
[17] LI Pan, ZHANG Xiaohong. Integrating GPS withGLONASS to Accelerate Convergence and Initialization Times of Precise Point Positioning[J].GPS Solutions, 2014, 18(3): 461-471.
[18] CAI Changsheng,GAO Yang. Modeling and Assessment of Combined GPS-GLONASS Precise Point Positioning[J]. GPS Solutions, 2013, 17(2): 223-236.
[19] CHEN Junping, XIAO Pei, ZHANG Yize, et al. GPS-GLONASS System Bias Estimation and Application in GPS-GLONASS Combined Positioning[C]//SUN Jiadong, JIAO Wenhai, WU Haitao,et al. Lecture Notes in Electrical Engineering: China Satellite Navigation Conference (CSNC) 2013 Proceedings, 2013, 244: 323-333.
[20] ZHANG Xiaohong, ZUO Xiang, LI Pan, et al. ConvergenceTime and Positioning Accuracy Comparison between BDS and GPS Precise Point Positioning[J]. Acta Geodaeticaet Cartographica Sinica, 2015, 44(3): 250-256. (张小红, 左翔, 李盼, 等. BDS/GPS精密单点定位收敛时间与定位精度的比较[J]. 测绘学报, 2015, 44(3): 250-256.)
[21] CHEN Junping, ZHANG Yize, WANG Jungang, et al. A Simplified and Unified Model of Multi-GNSS Precise Point Positioning[J]. Advances in Space Research, 2015, 55(1): 125-134.
