PPP网解UPD模糊度固定的无基站差分大型CORS站整网快速精密解算

Rapid and precise solution of the whole network of thousands of stations in China based on PPP network solution by UPD fixed technology

本文利用“国家基准一期工程”和上千全国部分省市CORS站的GNSS观测资料,基于PPP网解UPD模糊度固定技术实现了区域内无基站差分毫米级定位以及上千全国CORS站整网一次快速精密解算,这对于保障国家应急测绘快速响应、实现灾区基准快速建立以及快速获取和恢复国家统一坐标框架基准站坐标等具有重要的实用价值意义。首先,选取2015年8月1—31日198个国家GNSS连续运行基准站计算卫星端的宽巷、窄巷UPD,采用PPP网解UPD模糊度固定技术,对这些GNSS测站的载波相位进行模糊度固定:宽巷模糊度31 d固定率平均值在80%以上的测站共有193个;窄巷模糊度31 d固定率平均值在60%以上的测站共有165个。其次,对PPP整网一次快速解算定位结果进行统计分析,结果表明:31 d整网解算在NEU 3个方向的RMS分别为2.8、3.9、5.3 mm;标准差分别为2.1、3.2、6.7 mm。再者,使用中国区域内5个IGS观测站进行无基站差分精密定位,与SOPAC单天解ITRF2008框架下历元坐标的对比分析表明,31 d单日解外符合精度水平及高程方向均相差在毫米量级。最后,利用上述GNSS基准站解算出来的卫星端的宽、窄巷UPD(31 d),依次对2015年8月1—31日全国及部分省市1195个CORS站观测数据进行载波相位模糊度固定,得到无模糊度的精确相位观测值,从而使法方程中待估模糊度参数减少,克服了基准站网规模和测站个数的限制,实现了上千CORS站整网一次快速解算,对31 d月平均解与国际知名软件GAMIT/GLOBK的双差月解结果(2015年国家基础测绘任务成果)进行比较,结果显示,NEU 3个方向上差异在1 cm以内的测站分别为99.92%、99.33%、79.83%,其中U方向相差在1.5 cm为93.22%。综上所述,PPP网解UPD模糊度固定技术的方法,确保了区域内无基站精密定位、大网快速解算的精度和效率,能够满足灾区及国家坐标框架基准站坐标快速解算与恢复的迫切需求。

Based on the PPP network solution by UPD(uncalibrated phase delay)ambiguity fixed technology,millimeter-level regional differential positioning without a base station and whole network disposable rapid precise solution can be achieved using GNSS data from the first phase of the National Datum Engineering of China and thousands of national CORS stations in each province or municipality.This is of great practical significance to enhance the ability of national survey to meet the urgent need,to realize the rapid establishment of benchmark in the disaster area and to quickly reconstruct the national unified coordinate frame and its service.Firstly,the UPD of wide-lane and narrow-lane are estimated using national GNSS data of 198 continuously operating reference stations during August in 2015.Then,the float carrier phase ambiguities from each GNSS station are fixed using the UPD of wide-lane and narrow-lane until those from all the GNSS stations are completed.The results indicate that there are 193 stations where average successfully fixed rate of wide-lane ambiguities is above 80%and 165 stations where that of narrow-lane ambiguities is above 60%.In addition,the root mean square of whole network solution in North,East and Up direction are 2.8,3.9 and 5.3 mm,respectively;the standard deviation of whole network solution in North,East and Up direction are 2.1,3.2 and 6.7 mm,respectively.Compared with single day solutions by SOPAC under the ITRF2008,the external errors in horizontal and vertical direction are both at millimeter level.Finally,we can obtain the accurately phase observations without ambiguities,which are fixed using the UPD of wide-lane and narrow-lane,from 1195 GNSS stations during August in 2015.The whole network disposable solution covering thousands of stations can be achieved using the accurately phase observations without ambiguities,which could reduce the number of ambiguity parameters and overcome the restriction of network in size and the number of stations.The double-difference monthly solution by GAMIT/GLOBK are used to validate the results by the above method.99.92%,99.33%and 79.83%stations share a difference of less than 1 cm in North,East and Up direction,respectively.Wherein,the Up-component difference of 93.22%stations are within 1.5 cm.In summary,the accuracy and efficiency of both regional precise positioning without a base station and rapidly calculating for GNSS huge network could be ensured based on the PPP network solution by UPD ambiguity fixed technology.Furthermore,it can also meet the urgent demand to fast reconstruct national coordinate frame and that in disaster area.