Application of robust Vondrak filtering method in time-frequency transmission
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摘要: 时间频率传递的结果会受到非模型化误差和观测噪声的影响,其噪声常为高频信号,构建低通滤波器可在一定程度上消除观测值序列中的高频噪声信号. 本文对Vondrak滤波函数的本质进行剖析,通过IGG3算法对钟差序列进行定权并采用频率响应法选择适合的滤波因子;对不同的链路分别进行卫星双向时间频率传递(two-way satellite time and frequency transfer, TWSTFT)、基于软件接收机的卫星双向时间传递(two-way satellite time and frequency transfer based on software defined receiver, SDR-TWSTFT)和短基线共视时间频率传递实验,并对钟差结果采用抗差Vondrak滤波进行平滑去噪. 结果表明:滤波后的钟差序列能够很好地反映原始钟差序列的趋势;平滑后的TWSTFT钟差结果,日波动效应得到了有效的抑制,精度有明显提升;对于共视钟差结果,精度有明显提升,与精密单点定位(precise point positioning,PPP)时间传递结果的差值保持在−1.0~1.0 ns范围内.
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关键词:
- 抗差Vondrak滤波 /
- 平滑因子 /
- 共视时间频率传递 /
- 卫星双向时间频率传递(TWSTFT) /
- 精密单点定位(PPP)
Abstract: The results of time-frequency transfer will be affected by the non-modeling error and observation noise, which is often high-frequency signals, and the construction of low-pass filter can eliminate the high-frequency noise signals in the observation sequence to a certain extent. In this paper, we analyze the nature of the Vondrak filter function, weight the clock difference sequence by the IGG3 algorithm and select the suitable filtering factor by the frequency response method; we conduct the satellite two-way time and frequency transfer experiment (TWSTFT), the satellite two-way time and frequency transfer experiment based on the software receiver (SDR-TWSTFT), and the short-baseline common-view time and frequency transfer experiment on the different links, and use the short-baseline common-sight time and frequency transfer method on the results. experiments, and the clock difference results are smoothed and denoised by anti-differential Vondrak filtering. The results show that: the filtered clock sequence can well reflect the trend of the original clock sequence; the daily fluctuation effect is effectively suppressed and the accuracy of the smoothed TWSTFT clock result is significantly improved; the accuracy of the common-view clock result is significantly improved, and the difference between the result and the precise point positiening (PPP) timing result is kept in the range of −1.0 to 1.0 ns.-
Key words:
- robust Vondrak filtering /
- smoothing factor /
- common-view time-frequency transfer /
- TWSTFT /
- PPP
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表 1 滤波前后RMSE
ns 项目 NIM-NTSC链路 OP-PTB链路 滤波前 滤波后 滤波前 滤波后 RMSE 1.95 1.64 0.14 0.09 极大值 79.86 78.47 2.33 2.18 极小值 70.17 72.36 1.60 1.87 极差 9.69 6.11 0.73 0.31 表 2 滤波前后RMSE
项目 滤波前/ns 滤波后/ns PPP/ns 提升率/% RMSE 1.59 1.08 0.77 32 极大值 259.57 253.08 251.57 - 极小值 242.55 246.98 248.42 - 极差 17.01 6.10 3.15 64 -
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