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Elman Neural Network Based on Particle Swarm Optimization for Prediction of GPS Rapid clock Bias

Elman Neural Network Based on Particle Swarm Optimization fo...

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第十三届中国卫星导航年会

作者： Yifeng Liang Jiangning Xu Miao Wu Naval Univ.of Engineering

To improve the accuracy of the satellite rapid clock bias, a modified Elman neural network clock bias prediction method based on particle swarm optimization（PSO） algorithm is proposed. The Elman recurrent neural network is introduced to predict the clock bias, its weights and thresholds are improved by PSO algorithm to improve the training speed and prediction accuracy. Then,the optimization method is applied to the rapid clock bias prediction, and the steps of using this method for the rapid clock bias prediction are given. Finally,the optimization method is compared with common quadratic polynomial model, gray model and ultra rapid clock bias product IGU-P. The results show that the PSO-Elman model achieves high accuracy and stability for four different types of GPS satellite clock, and its prediction accuracy and stability improved by 85%, 74%, 89% and 71%, 53%, 28% compared with QPM,GM（1,1） and IGU-P products, respectively.

关键词： satellite atomic clock clock bias prediction Elman neural network Particle Swarm optimization

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Research on Prediction and Characteristics of Periodic in BDS/GPS satellite clocks

Research on Prediction and Characteristics of Periodic in BD...

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第九届中国卫星导航学术年会

作者： Jie Zheng Xiangyu Zhu Meijun Guo Guang Sun Xiaolin Jia Shuangqin Li Xi’an Aerospace Remote Sensing Data Technology Co. Ltd. Xian Research Institute of Surveying and Mapping

The prediction accuracy of satellite clock bias(SCB) directly affects the performance of navigation system. According to the spectrum analysis method, the periodic characteristics of satellite clocks are analyzed, and using precise SCB data of BDS/GPS satellite the prediction tests are conducted, and then we build the forecast model considering periodic items. Based on this, the influence of the number of periodic items on the result of SCB prediction is analyzed. The effect of SCB prediction between periodic term model and quadratic polynomial model is compared, and the SCB prediction performance of different types of satellites is summarized. Experimental results show that the periodic variation of satellites are significant. The periodic items of BDS are 24 h, 12 h and 8 h, and the periodic items of GPS are 24 h, 12 h and 6 h. The number of periodic items affects the prediction results. The prediction accuracy of BDS using 2 to 3 main periodic items is the best, and the prediction accuracy of GPS using 3 to 4 main periodic items is the best. Compared with the quadratic polynomial prediction model, the prediction accuracy of the proposed model with additional periodic items can be improved by 1 ns.

关键词： BDS GPS satellite atomic clock clock offset prediction

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The Long-term Performance Analysis and Comparision of BDS On-board atomic clock Based on Precise clock Products of IGS Analysis Centers

The Long-term Performance Analysis and Comparision of BDS On...

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第九届中国卫星导航学术年会

作者： Huijie Xue Tianhe Xu Qingsong Ai Shengchao Wang School of Geology Engineering and Surveying Chang an UniversityXi an Institute of Space Science Shandong University State Key Laboratory of Geo-information Engineering Institute of Geodesy and Geophysics. Chinese Academy of Sciences

As an important load of BDS, the performance of satellite-borne atomic clock directly affects the service level of navigation system. Based on the requirements of navigation system on atomic clocks in orbit, the performance of BDS spaceborne atomic clocks has been studied in recent years. Precise clock products of two IGS analysis centers wum and gbm with sampling interval of 300 seconds from 2014 to 2017 were adopted. The BDS spaceborne atomic clocks were evaluated and analyzed from accuracy, drift rate and stability respectively. The results indicate that, overall, MEO satellite clock performance is the best, followed by IGSO satellite clock, the worst is GEO satellite clock;the accuracy, the daily drift rate and the 10000 seconds stability fluctuate at 7 × 10 4 × 10,-3 × 10 3 × 10, 3 × 10 1.5 × 10 respectively. In terms of drift rate and the 10000 seconds stability, the results of performance analysis of GEO satellite clock using two different precise clock products have great differences, while those of IGSO and MEO satellite clocks have little difference.

关键词： BDS satellite atomic clock accuracy drift stability wum gbm

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