| In order to evaluate the signal in space(SIS)integrity of the Beidou regional system,this paper starts from the basic navigation information and enhanced service information of the Beidou D2 navigation message,and studies the SIS integrity of the message by analyzing the message.First of all,this paper summarizes the Beidou regional satellite navigation system,gives the current Beidou regional system service capability,and introduces the Wide Area Augmentation System.Focus on the D2 message from BDS GEO satellite and the WAAS message,and the similarities and differences between them are given by comparing the D2 message and the WAAS message.Secondly,the Beidou D2 message is analyzed.The analytic message is applied in error analysis process and location calculation process,then,the range and length of the message used in each process are given.The correctness of the analysis of the message is determined by comparing the calculated value with the given value.Thirdly,the evaluation index and integrity parameter monitoring algorithm of SIS is introduced.The integrity parameters in the D2 message are monitored in two parts: basic navigation information and differential enhancement information integrity monitoring.In addition,the calculation process of IURE,UDRE,RURA,GIVE and PL is also given.Finally,the scheme and monitoring results of SIS integrity evaluation of Beidou regional system using D2 message is given.From the monitoring results during the observation period,we can see that: the failure rate per day of the BDS No.9 satellite is lowest and the failure rate is 0.001,while the No.2 satellite is highest of the value0.021;satellite 1-5 differential precision is higher than satellite 6-10and13.MEO rank the last.Monitoring stations in some parts is less,the ionosphere vertical delay correction can not represent the true value;enhanced service information is conducive to improving the SIS alarm capability for its' fast update rate. |
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