A new approach to real-time precise point-positioning timing with International GNSS Service real-time service products
A new approach to real-time precise point-positioning timing with International GNSS Service real-time service products
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DOI：
10.1088/1361-6501/ab2fa5
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发表时间：
2019-09
影响因子：
2.4
通讯作者：
Yulong Ge;W. Qin;Ke Su;Xuhai Yang;Mingjun Ouyang;Feng Zhou;Xingwang Zhao
中科院分区：
文献类型：
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作者：
Yulong Ge;W. Qin;Ke Su;Xuhai Yang;Mingjun Ouyang;Feng Zhou;Xingwang Zhao
利用精密单点定位（PPP）技术进行实时精确授时一直是科学家们的研究热点。然而，实时精确的产品并不符合统一的时间尺度。因此，实时精密产品只能用于时间传递，而不能用于计时。此外，如果参考时间频繁地改变，则不能对接收器时钟偏移进行建模以进一步提高定时的准确性。在这项工作中，我们提出了一个精确的卫星定时方法，使用国际GNSS服务（IGS）的实时服务产品，获得用户的本地时间和UTC（k）之间的差异，直接使用全球导航卫星系统（GNSS）接收器。该方法基于三个步骤：（1）接收与UTC（k）相关的实时数据流和接收机观测值;（2）通过PPP方法将新的精确产品的参考时间与UTC（k）对齐，然后通过NTRIP广播新的精确产品（通过互联网协议进行RTCM的网络传输）;以及（3）使用GNSS接收器直接获得本地时间与UTC（k）之间的差，这可以由地球上任何地方的用户完成。我们的数值分析阐明了我们的精确定时方法如何使用IGS实时服务产品。首先，IGS最终产品发布的时序结果与接收器时钟结果之间的差的标准偏差（STD）约为0.2 ns。使用历元间约束模型，差异的STD值减少约2.76%-25.66%。第二，定时的频率稳定性与接收机时钟偏移IGS最终产品在长期稳定性方面具有良好的一致性，而具有历元间约束模型的定时的短期稳定性优于IGS最终产品。第三，当用白色噪声模型估计时钟偏移时，使用新产品和CLK 93产品获得的实时动态定位精度具有相似的水平。在三个坐标分量上，采用时间约束模型的定位精度比不采用时钟模型的定位精度分别提高了0.91%、2.54%和23.21%。
Real-time precise timing with the precise point-positioning (PPP) technique is of great interest for scientists. However, real-time precise products are not aligned to a unified time scale. Hence, real-time precise products can only be utilized for time transfer not for timing. Furthermore, if the reference time changes frequently, the receiver clock offset cannot be modelled to further improve the accuracy of timing. In this work, we present a precise satellite timing approach using International GNSS Service (IGS) real-time service products, obtaining the difference between the local time of the user and UTC(k) directly using a global navigation satellite systems (GNSS) receiver. This approach is based on three steps: (1) receiving real-time data streams and receiver observations connected to UTC(k); (2) aligning the reference time of the new precise products to UTC(k) by a PPP approach, with the new precise products then being broadcast via NTRIP (networked transport of RTCM via internet protocol); and (3) obtaining the difference between local time and UTC(k) directly using a GNSS receiver, which can be done by users anywhere on the Earth. Our numerical analyses clarify how our precise timing approach performs using IGS real-time service products. First, the standard deviation (STD) of the difference between the timing results and the receiver clock results released by the IGS final products is approximately 0.2 ns. The STD values of the difference are reduced by approximately 2.76%–25.66% using the between-epoch constraint model. Second, the frequency stability of the timing has a good consistency with the receiver clock offset from the IGS final products with regard to long-term stability, while the short-term stability of the timing with the between-epoch constraint model is better than that of IGS final products. Third, the real-time kinematic positioning accuracy obtained using the new products and CLK93 products is of a similar level when the clock offset is estimated with the white noise model. By using the new products, the positioning accuracy of the between-epoch constraint model is improved by 0.91%, 2.54% and 23.21% over the result without the clock model in three coordinate components.