Zou Junping, Wang Ahao, Wang Jiexian
College of Surveying and Geo-Informatics, Tongji University, Shanghai 200092, China.
College of Geoscience and Surveying Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China.
Sensors (Basel). 2021 Apr 18;21(8):2856. doi: 10.3390/s21082856.
High-precision and low-cost single-frequency precise point positioning (SF-PPP) has been attracting more and more attention in numerous global navigation satellite system (GNSS) applications. To provide the precise ionosphere delay and improve the positioning accuracy of the SF-PPP, the dual-frequency receiver, which receives dual-frequency observations, is used. Based on the serviced precise ionosphere delay, which is generated from the dual-frequency observations, the high-precision SF-PPP is realized. To further improve the accuracy of the SF-PPP and shorten its convergence time, the double-differenced (DD) ambiguity resolutions, which are generated from the DD algorithm, are introduced. This method avoids the estimation of fractional cycle bias (FCB) for the SF-PPP ambiguity. Here, we collected data from six stations of Shanghai China which was processed, and the corresponding results were analyzed. The results of the dual-frequency observations enhanced SF-PPP realize centimeter-level positioning. The difference between the results of two stations estimated with dual-frequency observations enhanced SF-PPP were compared with the relative positioning results computed with the DD algorithm. Experimental results showed that the relative positioning accuracy of the DD algorithm is slightly better than that of the dual-frequency observations enhanced SF-PPP. This could be explained by the effect of the float ambiguity resolutions on the positioning accuracy. The data was processed with the proposed method for the introduction of the DD ambiguity into SF-PPP and the results indicated that this method could improve the positioning accuracy and shorten the convergence time of the SF-PPP. The results could further improve the deformation monitoring ability of SF-PPP.
高精度低成本单频精密单点定位（SF-PPP）在众多全球导航卫星系统（GNSS）应用中越来越受到关注。为了提供精确的电离层延迟并提高SF-PPP的定位精度，采用了接收双频观测值的双频接收机。基于双频观测值生成的服务精密电离层延迟，实现了高精度的SF-PPP。为了进一步提高SF-PPP的精度并缩短其收敛时间，引入了由双差（DD）算法生成的双差模糊度解算。该方法避免了对SF-PPP模糊度的小数周期偏差（FCB）进行估计。在此，我们收集了中国上海六个站点的数据并进行处理，分析了相应结果。双频观测增强型SF-PPP的结果实现了厘米级定位。将双频观测增强型SF-PPP估计的两个站点结果与用DD算法计算的相对定位结果进行了比较。实验结果表明，DD算法的相对定位精度略优于双频观测增强型SF-PPP。这可以通过浮动模糊度解算对定位精度的影响来解释。用所提出的将DD模糊度引入SF-PPP的方法对数据进行了处理，结果表明该方法可以提高SF-PPP的定位精度并缩短其收敛时间。结果可以进一步提高SF-PPP的变形监测能力。
