基于接收机钟差约束的精密单点定位时间传递研究

精密单点定位(PPP)技术起初主要面向定位与导航等位置应用. 近年来，PPP技术逐渐成为时间传递等非定位应用的一种重要且有效的手段. 如今，具有更高稳定性的氢原子钟也被越来越多的测站用来提供时间频率基准. 而传统的PPP时间传递方法通常在数据处理时将接收机钟差参数视为白噪声(WN)参数进行处理，并未充分利用原子钟的高稳定特性. 因此，基于实测数据计算得到氢原子钟的经验方差，提出了一种接收机钟差参数的约束方法来提高PPP时间传递性能. 通过三条时间链路进行验证分析，结果表明:相较于传统的PPP时间传递方法，提出的基于接收机钟差约束的PPP时间传递方法在整体上具有更高的稳定性，其中短期稳定性可以实现量级的提升. 

Precise point positioning time transfer based on receiver clock offsets constraint

Precise point positioning (PPP) was originally developed for positioning and navigation applications. Recently it has gradually been accepted as an effective tool for non-positioning applications such as time transfer. Nowadays, more and more stations use the high stability Hydrogen atomic clock to provide datum of time and frequency. However, receiver clock offsets are generally regarded as white noise parameters in customary PPP time transfer method, which does fully utilize the high stability of Hydrogen masers. Therefore, we calculate the empirical variance of H-masers based on real GPS observations, and proposed a constraint method of receiver clock offsets between adjacent epochs to improve the performance of PPP time transfer. We confirm this model by three time links experiment. The results imply that, compared with the customary PPP time transfer method, our method has higher stability and the short-term stability can increase up to one order of magnitude.