Design And Implementation Of RAIM Availability Prediction System Of Train

With the development of GNSS satellite navigation system,the application in the field of high-speed railway is also being developed.Using GNSS satellite navigation system,there are susceptible to interference and satellite integrity problems.Satellite navigation signal receiver is equipped with receiver autonomous integrity monitoring(RAIM)function,which is the development of satellite integrity problems.It makes use of the redundant information of the GPS satellite to test the consistency of the GPS navigation solutions,so as to achieve the purpose of integrity monitoring.RAIM prediction technique is a technique to indicate whether RAIM is available.In some cases,such as when the satellite geometric distribution is not good,there will be a so-called "RAIM hole",when RAIM is not available.In this case,the receiver can not own integrity monitoring,and could not be determined at this time of the GPS satellite,which will bring security risks for each system using GPS signals.Therefore,it is necessary to predict whether RAIM can be used to ensure the security of the railway system when using the satellite navigation system.Based on the research on the application of RAIM in the field of aviation,the design and implementation of RAIM availability prediction system of train is researched,according to railway satellite navigation system on the integrity of the demand,in view of the existing railway system using GPS satellite navigation system of satellite integrity monitoring security risk problem.The main contents are as follows: First of all,based on reading a large number of Chinese and foreign literature,from the principle of GNSS positioning to RAIM availability prediction algorithm,the introduction of related technologies is introduced in accordance with the cause and effect.A clearer understanding of RAIM availability prediction is produced.Secondly,in the process of the design and implementation of the system,according to the business requirements of the system,the network topology and the system function structure are designed.The functional modules of the system are divided into data processing module,RAIM availability prediction module and RAIM availability prediction result release module.Among them,the data processing module is the most basic function modules of the system,the module of operation data processing,including data acquisition,processing and access.The RAIM availability prediction module is equipped with the most important functional tasks of the railway RAIM availability prediction system,and carries on the forecast of RAIM availability prediction,which can meet the need of the forecast by timing prediction and real-time prediction.The RAIM usability prediction results release module completes the interaction between the system and the user.The system function modules and the system database are designed and implemented.Then,after the completion of the design and implementation of the system,the system carrys out the relevant functional testing and non functional testing.The system can realize all the functions of the system in the requirement analysis phase through the relevant test cases.Finally,the work in the paper is summarized.According to the shortcomings of the paper,the future work is prospected.Based on the above research,by using the RAIM availability prediction system of train,the availability of RAIM is predicted for railway stations and railway lines,and the availability information of RAIM is given,which can be used to assist railway dispatching so as to ensure the reliability of train positioning system,and to ensure the safety of train operation.