附加双差模糊度网解约束的GNSS相位延迟估计

针对现有相位延迟估计方法未利用双差模糊度网解约束的特点，提出了一种附加双差模糊度网解约束的相位延迟估计方法。首先以整周双差模糊度网解为真值更新精密单点定位(PPP)估计的非差浮点模糊度，再通过网平差法估计未校正相位延迟(UPD)。实验结果表明，PPP双差模糊度与双差模糊度网解一致性好，其宽、窄巷中误差分别为0.07周和0.11周，误差大于1周的PPP双差模糊度主要出现在卫星初升阶段。约束改变了非差浮点模糊度，从而改变了参与UPD网平差的测站，使14%新升起卫星的窄巷UPD在短时间内较无约束有大于0.2周的差异。附加约束/无约束的全天星间单差UPD差异在大于99.9%的置信水平下满足零均值假设，表明整周双差模糊度网解约束方法与无约束方法估计UPD相关产品具有等效性。研究结果可为参考网非差模糊度解算和PPP与网络实时动态定位(RTK)的融合工作提供参考。

A method for GNSS phase delay estimation with double-differenced network solution ambiguity constraint

Aiming at the feature of existing methods for phase delay estimation where double-differenced ambiguity network solutions are not applied, a method for phase delay estimation with the constraint of double-differenced ambiguity network solution is proposed. Firstly, integer double-differenced network ambiguities are utilized as real values to update undifferenced float ambiguities estimated by precise point positioning (PPP), uncalibrated phase delay (UPD) estimation is then performed by net-adjustment method. Experimental results show that PPP double-differenced ambiguities and double-differenced ambiguities network solutions show good accordance, with wide/narrow lane standard deviation being 0.07 cycle and 0.11 cycle respectively. PPP double-differenced ambiguities with biases greater than 1 cycle mainly appear in the newly-ascending periods of satellites. The constraint alters undifferenced float ambiguity and thus changes stations engaged in UPD net-adjustment, causing narrow lane UPD of around 14% of newly-ascending satellites to appear differences greater than 0.2 cycle in a short period compared to the non-constraint case. The difference between with/without constraint inter-satellites single-differenced UPD of a whole day satisfies the zero-mean hypothesis at a confidence level greater than 99.9%, indicating an equivalence between the integer double-differenced network ambiguities constrained method and the non-constrained method for the estimation of UPD and related products. The result of the research can provide reference to the work about the resolution of undifferenced ambiguities of referential networks and the fusion of PPP and network real-time kinematic (RTK).