融入GNSS星钟频率稳定性的超快速卫星钟差预报模型

An Improved GNSS Ultra-Rapid Clock Offset Predicted Model by Inserting the Frequency Stability of the Satellite Onboard Atomic Clocks

  • 摘要: 全球导航卫星系统(GNSS)超快速预报钟差产品是高精度实时与近实时位置服务的时间基准之一,然而基于超快速钟差估计序列的建模与预报过程易受噪声与模型可靠性等因素影响。因此,本文构建了一种融入GNSS星钟频率稳定性的超快速卫星钟差预报新模型。首先,在卫星钟差估计模型中引入钟差速度与加速度等参数,提取更加平稳的GNSS钟差状态序列;其次,基于构建的长短时记忆(LSTM)与多层感知(MLP)组合模型进行GNSS卫星钟差状态参数预报,充分顾及建模参数的时空相关性;最后,利用滑动窗口建模钟差连续状态预报参数,通过时间积分恢复卫星预报钟差增量。实验结果表明,估计的GNSS钟差状态参数稳定性较传统钟差序列显著提升;且以钟差状态参数为基础的预报模型较传统超快速钟差预报过程可分别至少提升6h、12h与24h预报精度14.0%、7.9%与22.3%;基于积分恢复的预报钟差参数可分别改善静态PPP的E、N、U方向定位精度与收敛时间74.0%、34.3%、51.4%和46.5%、42.7%、63.3%。因此,本文提出的GNSS钟差预报模型可显著提升超快速钟差产品质量,有效补充了快速精密位置服务产品。

     

    Abstract: Objectives: the predicted Global Navigation Satellite System (GNSS) ultra-rapid clock offset products are the one of time references of high-precision real-time and near-real-time location services. However, the quality of traditional ultra-rapid clock offset products are directly affected by the noise and reliability of the estimated ultra-rapid clock offset series. In this research, an improved GNSS ultra-rapid clock offset predicted model by inserting the frequency stability of the satellite onboard atomic clocks is proposed. Methods: first, the velocity and acceleration terms of clock offset are introducing into its estimation equations to acquire the stabler origin series than the traditionally estimated clock offsets. Second, the velocity and acceleration parameters are predicted based on the combination of long short-term memory (LSTM) and (Multilayer Perceptron) MLP models to fully consider the spatiotemporal correlation of the clock offset state series. Third, the sliding window is used to model the continuously predicted clock offset state series to integrate the epoch increment of predicted clock offsets. Results: according to the experiments, it is indicated that the stability of clock offset velocity and acceleration is significantly improved compared with the traditional ultra-rapid clock offset series. Meanwhile, the accuracy of the predicted ultra-rapid clock offset based on the proposed model can be improved at least 14.0%, 7.9% and 22.3% within 6h, 12h and 24h, respectively. In addition, the recovered predicted ultra-rapid clock offset based on the integration can optimize the positioning accuracy and convergence time of static PPP solutions in E, N and U directions with 74.0%、 34.3%、 51.4% and 46.5%、 42.7%、 63.3%. Conclusions: therefore, the quality of GNSS satellite ultra-rapid clock offset products can be improved based on the proposed model, which will effectively supplement to the rapid precision location service products.

     

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