面向提高精度和可用性的卫星导航数据处理技术研究

发布时间：2018-11-11 09:49

【摘要】：精度和可用性是卫星导航系统的重要指标。传统包含5状态变量的粗时定位方法能够在植被遮挡、室内等弱信号环境下利用亚毫秒伪距实现定位,从而提高服务可用性,然而其需要已知接收机概略位置。此外,北斗卫星导航系统采用混合星座设计,具有GEO卫星电文速率高、广播格网点电离层信息等特点。GEO卫星的高电文速率为实现快速定位提供了可能,合理使用区域格网点电离层信息能有效提高单点定位精度。在上述背景下,论文围绕提高卫星导航系统精度和可用性展开研究并取得以下成果:(1)针对传统广播历书直接拟合方法获得历书参数精度较低的问题,提出基于长半轴补偿的广播历书改进计算方法,通过在参数拟合时增加角速度变化量并将其转换为长半轴补偿值的方法计算广播历书参数。算例表明,该方法能使历书参数的URE由传统方法的约2000米降低为优于900米。此外,重新定义包含角速度变化量的9参数历书,能够使URE再提高一倍以上。(2)针对传统粗时定位方法需要已知接收机概略位置的问题,提出基于伪距模糊搜索的改进粗时定位方法和高精度时钟辅助下的模糊搜索快速定位方法,并提出使用星间距离与最大伪距差值的关系减小搜索空间,能够在概略位置未知时实现快速定位。算例表明,在信号捕获后的亚毫秒伪距情况,使用IGS的mars测站L1频点观测数据,改进粗时定位方法的平均备选模糊组合数约为672,在1、3和5秒偏差的情况下,定位成功率分别为99.96%、99.86%和99.79%,其他测站成功率可达100%。另外,遍历多个测站观测数据表明,当辅助时间精度优于15微秒时,能够100%实现快速定位;优于25微秒时,能够99%实现快速定位。(3)利用北斗系统中GEO卫星导航电文速率高、帧同步时间短的特点,分别提出高程假设与多普勒辅助的快速定位方法,能够在非GEO卫星完成帧同步之前利用GEO伪距和辅助信息计算概略位置并实现快速定位,同时避免了GEO卫星粗定位可能出现解算失败的问题。算例表明,在高程辅助下即使只有3颗GEO卫星伪距可用仍可以实现快速定位;在有充足多普勒信息辅助的情况下即使GEO观测伪距数小于3,也可以实现快速定位。(4)针对仅部分伪距可使用电离层格网修正时难以确定格网和Klobuchar模型修正后定位精度优劣的问题,提出基于位置精度因子PDOP比较的电离层修正方法。通过利用格网和Klobuchar模型可修正观测量的PDOP构建检验量用于选择电离层修正方法以提高定位精度。算例表明,该方法的定位精度能达到甚至略优于格网和Klobuchar模型修正的较优结果,与不进行选择的最坏情况相比kun1、chu1和lah1测站定位精度分别提高18.1%、16.5%和19.9%。最后,总结论文主要工作。论文研究成果已应用于卫星导航系统的各型号接收机和信号源的项目研制中。
[Abstract]:Precision and availability are important indexes of satellite navigation system. The traditional coarse time localization method with 5 state variables can be used to locate in the weak signal environment such as vegetation shelter and indoor so as to improve the availability of service. However it needs to know the approximate position of the receiver. In addition, Beidou satellite navigation system is designed by hybrid constellation, which has the characteristics of high GEO satellite message rate and broadcasting grid ionospheric information. The high message rate of GEO satellite makes it possible to realize fast positioning. Reasonable use of the ionospheric information of the regional grid can effectively improve the accuracy of single point positioning. Under the above background, the thesis focuses on improving the accuracy and availability of satellite navigation system and obtains the following results: (1) aiming at the problem of low precision of obtaining almanac parameters by direct fitting method of traditional broadcast almanac, An improved calculation method of broadcast almanac based on long half axis compensation is proposed. The broadcast almanac parameters are calculated by increasing the variation of angular velocity and converting it to the compensation value of long half axis when the parameters are fitted. The example shows that the URE of the almanac parameters can be reduced from about 2000 meters to better than 900m by the traditional method. In addition, the redefinition of the 9-parameter almanac, which contains the variation of angular velocity, can double the URE. (2) to solve the problem that the traditional coarse time localization method needs to know the approximate position of the receiver, An improved coarse time location method based on pseudo-range fuzzy search and a fast location method based on high precision clock are proposed. The relationship between the distance between satellites and the maximum pseudo-range difference is used to reduce the search space. Can realize the quick localization when the approximate position is unknown. Numerical examples show that in the case of sub-millisecond pseudo-range after signal acquisition, the average alternative fuzzy combination number of the improved coarse time location method is about 672 using the L1 frequency observation data of the mars station of IGS, and the deviation of 1 / 3 and 5 seconds is obtained. The success rate of location was 99.96% and 99.79% respectively, and the success rate of other stations was 100. In addition, traversing the observation data of multiple stations shows that when the precision of auxiliary time is better than 15 microseconds, the fast positioning can be achieved in 100%. When it is better than 25 microseconds, it can achieve fast positioning in 99%. (3) taking advantage of the high speed and short frame synchronization time of GEO satellite navigation message in Beidou system, the elevation hypothesis and Doppler assisted fast positioning method are put forward, respectively. It can use GEO pseudo-range and auxiliary information to calculate the approximate position and realize the fast positioning before the frame synchronization of the non-GEO satellite. At the same time, it can avoid the problem of the solution failure of the rough positioning of the GEO satellite. An example shows that even if only three GEO satellites can be used in pseudo-range, rapid positioning can be achieved. Even if the GEO observation pseudo-range is less than 3, with sufficient Doppler information, (4) aiming at the problem that it is difficult to determine the positioning accuracy after the correction of the grid and Klobuchar model when only partial pseudo-distance can be corrected by ionospheric grid, an ionospheric correction method based on the PDOP comparison of position accuracy factor is proposed. By using grid and Klobuchar model, the PDOP construction test of observational data can be modified to select the ionospheric correction method to improve the positioning accuracy. Numerical examples show that the accuracy of this method is even slightly better than that of grid and Klobuchar model modification. Compared with the worst case without selection, the positioning accuracy of kun1,chu1 and lah1 stations is increased by 18.1g, respectively. 16.5% and 19.9% respectively. Finally, the paper summarizes the main work. The research results of this paper have been applied to the development of various types of receiver and signal source of satellite navigation system.
【学位授予单位】：国防科学技术大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN967.1

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