北斗/GNSS广域网络RTK关键技术研究

In order to decrease the cost, share the resources and provide consistent services, the divided BeidDou/GNSS network RTK systems must become a whole real time high precision service system, which will include thousands of GNSS reference stations and provide service for thousands of users in the whole country. Moreover, the services of the new system will involve lots of new personal safety fields, such as automatic driving, civil aviation. However, the traditional regional network RTK technologies for a province or a city cannot meet the above requirements. A service gap exists between two neighboring network RTK systems, and the allowable maximal number of reference stations is about 300. Moreover, lack of integrity monitoring function is another defect. Considering the other two technologies, PPP-RTK and wide area real-time PPP cannot be compatible with many current widely used RTK terminals because the content and format of the corrections and the terminal’s positioning algorithm are different. In addition, a 15 to 30 minutes’ initialization time for the wide area real-time PPP cannot meet the requirements of the most real-time users. Herein, we propose a set of theory and methods of BeiDou/GNSS wide area network RTK system to ensure real-time cm-level positioning service for users in the whole country. The key technologies of our project include the reference network data processing over 10,000 stations, the broadcast service for massive users, the real-time coordinate service and the integrity monitoring. The research of our project provides supports of the theoretical basis and the technology and algorithm for the countrywide real-time cm-level BeiDou/GNSS ground-based augmentation system with low-cost, high-reliability and high-compatibility.

为了节省建设成本、资源共享、统一服务，我国分散的省市级北斗/GNSS网络RTK系统必将发展为全国统一的实时厘米级定位服务系统，其中基准站数量将突破万个、用户数以万计、服务对象由传统测绘发展到涉及人身安全的自动驾驶、民航等用户。但是目前以省、市为单位的区域北斗/GNSS网络RTK技术在跨区域服务、基准站数据处理能力、用户服务能力、完备性监测性能等方面都无法满足这一需求。近年来发展起来的PPP-RTK和广域实时精密定位技术则由于播发信息内容和格式、终端算法不同，无法兼容广泛应用的RTK终端。另外后广域实时精密定位技术还需要至少15分钟的初始化时间收敛到厘米级。因此本项目提出北斗/GNSS广域网络RTK技术，突破全国范围过万基准站数据实时处理、海量用户信息播发服务、实时统一坐标服务、完备性监测等关键技术，为我国建设低成本、高可靠、高兼容性的全国实时厘米级北斗地基增强系统提供理论、技术和算法支持。

针对现有实时精密单点定位和PPP-RTK技术存在的问题，本项目在区域网络RTK技术的基础上，提出了北斗/GNSS广域网络RTK技术。通过分析比较不同方法的时效性、可靠性、准确性，最终得出在一定条件下的最优的北斗/GNSS广域网络RTK基准站网快速处理方法。提出了一种自适应格网播发服务技术，解决海量用户和非VRS模式下的基准站坐标保密的问题。在坐标框架使用与实时坐标服务方面，研究如何确定广域网络RTK基准站网模糊度解算和误差改正数计算的坐标系统，安全、可靠、便捷的为用户提供高精度定位服务。在完备性监测方面，开创性地提出了一种不另外设监测站、基准站接收机两用的完备性监测模式，降低成本并保证高精度定位服务精确可信。同时，本项目完成了预期的研究任务，以该项目成果为重要依托，取得了丰硕的研究成果：获得测绘科学技术奖特等奖一项和卫星导航定位创新应用奖一项；申请了与项目研究内容相关的发明专利4项，软件著作权一项；在国内外学术期刊上发表了学术论文10篇，其中SCI收录9篇；培养了6名硕士和博士研究生，顺利毕业取得武汉大学研究生学位。本项目的研究成果已经成功应用于广东、新疆、山东等省CORS系统建设和服务中，在建立全国实时厘米级北斗地基增强系统方面具有重要的科学意义和现实实用价值。