National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China.
Key Laboratory of Precise Positioning and Timing Technology, Chinese Academy of Sciences, Xi'an 710600, China.
Sensors (Basel). 2021 Jan 11;21(2):466. doi: 10.3390/s21020466.
Satellite timing is an effective and convenient method that has been widely accepted in the time community. The key to satellite timing is obtaining a clean receiver clock offset. In this paper, instead of regarding the receiver clock offset as white noise, a two-state stochastic clock model involving three kinds of noise was conceived and used in PPP filter estimation. The influence of clock type and sampling time on satellite timing performance was first analysed. In addition, the kinematic scheme and static scheme were both investigated for meeting the demands of multi-occasional users. The values show that the model works well for both the kinematic scheme and static scheme; in contrast to that of the white noise model, the timing stability is enhanced at all the sampling times. For the six stations, especially when the averaging time is less than 1000 s, the average stability improvement values of the kinematic scheme are 75.53, 43.24, 75.00, 69.05, 40.57, and 25.45%, and the average improvement values of the static scheme are 65.49, 77.94, 56.71, 60.78, 64.41, and 39.41%. Furthermore, the enhancement magnitude is related to clock type. For a high-stability clock, the improvement of the kinematic scheme is greater than that of the static scheme, whereas for a low-stability clock, the improvement of the kinematic scheme is less than that of the static scheme.
卫星授时是时间领域广泛接受的一种有效且便捷的方法。卫星授时的关键是获取干净的接收机钟差。本文中，我们没有将接收机钟差视为白噪声，而是设想了一种包含三种噪声的两状态随机钟模型，并将其应用于 PPP 滤波估计中。首先分析了钟差类型和采样时间对卫星定时性能的影响。此外，还研究了动态方案和静态方案，以满足多用户的需求。结果表明，该模型在动态方案和静态方案中均表现良好；与白噪声模型相比，在所有采样时间下，定时稳定性都得到了提高。对于六个站，特别是当平均时间小于 1000 s 时，动态方案的平均稳定性改善值分别为 75.53%、43.24%、75.00%、69.05%、40.57%和 25.45%，静态方案的平均改善值分别为 65.49%、77.94%、56.71%、60.78%、64.41%和 39.41%。此外，增强幅度与钟差类型有关。对于高稳定性的钟差，动态方案的改善大于静态方案；而对于低稳定性的钟差，动态方案的改善小于静态方案。
