Research And Realization Of Software Defined Receiver-based Integrity Monitoring Method For Satellite Positioning

Train positioning system is an important element of the train operation control system.Safety is critically required in the satellite positioning-based train operation control systems.In practical operations,the satellite-based train positioning system may lose its capability of providing safe and reliable positioning determination results due to the existing or potential faults in satellite measurements.Therefore,it is of great significance to design and realize the software-based satellite navigation receiver platform with the integrity monitoring capability.That will contribute to the detection and isolation of existing faulty or abnormal measurement information,and achieve the trust worthy positioning for railway trains,which is significant to the safety assurance of the train control systems.The main contribution of this paper can be summarized as follows.(1)According to the principle of the Global Navigation Satellite System(GNSS),the signal processing of the satellite navigation receiver,from satellite acquisition to navigation computation,is analyzed.The key models of the receiver are established,including the capture,tracking and position computing.(2)Based on the analysis of satellite positioning errors and the corresponding characteristics,the fault models of GNSS are established.With this basis,the integrity monitoring logic is designed for a software receiver platform.(3)The general architecture of the software satellite navigation receiver platform with the integrity monitoring capability is designed.Based on that,the main modules of the software platform are realized.The autonomous integrity monitoring function is effectively achieved under a software-based satellite positioning environment.Using the collected satellite data,the functions of this platform are validated.The developed software receiver platform in this paper,is capable of combining the software-based navigation function with the autonomous integrity monitoring.With the satellite data collected from both the static and dynamical conditions,position determination and receiver autonomous integrity monitoring functions are tested and verified,which demonstrate that faults in satellite measurements could be detected,evaluated and isolated.The results of this paper are able to generate reliable and trustworthy positioning information,which can provide great support to the train control systems and other related systems.Furthermore,it will help to solve the safety risks in GNSS-based train positioning under the faulty measuring conditions,and establish an effective approach to realize receiver integrity monitoring at the front end of the GNSS receiver.