GNSS双频导航信号用户完好性监测机制研究

Research on User Integrity Monitor Mechanism with GNSS Dual-frequency Navigation Signals

用户完好性监测指标通常被用于衡量导航信息的可信度,针对单个卫星导航系统用户完好性监测指标过高、可用性较差的问题,提出一种全球导航卫星系统(GNSS)多系统双频信号联合完好性监测机制,该监测机制使用一定完好性风险分配值下的保护门限作为联合观测下的监测指标;另外,为了确保各种监测假设下的用户完好性,分别讨论了无故障及一颗卫星故障假设下的伪距观测误差获取、保护门限计算以及完好性风险指标分配等问题。仿真结果表明该用户监测机制可有效降低保护门限、提高可用性,在用于I类精密进近时全球大部分区域用户的可用性水平大于95%。

User integrity denotes the measure of the trust the user has in the navigation information. However when a single system navigation signal is available, the aviation users will have poor integrity and low availability. Therefore, integrity monitoring mechanisms are developed which are based on the protection levels and use multi-systems and dual-frequency navigation signals. In order to validate user integrity under fault-free and faulty assumptions, a pseudo-range error estima- tion, the protection level equations under different assumptions and the fixable integrity risk allocation are studied in detail. The results of the navigation performance simulation show that： the combined observation can effectively reduce the user protection level and improve the availability. In most regions of the world the availability exceeds 95% when it is used for Category I precision approach and landing.