The Research And Implementation Of Precision Timing Based On GPS/BDⅡ

In the field of developing aerospace, control systems have very strict requirements of thesynchronization of time, high precision of the time reference plays an important role in thelaunch and flight tests. In the process of space launch test of missiles, rockets and satellites,in order to ensure the monitoring and control equipments to complete monitoring and controltasks collaboratively on the time, the time reference provided by a variety of ground-basedmonitoring equipment must be synchronized with high accuracy. In the current,high-precision timing techniques almost rely on GPS timing system, but the GPS timingsystem is controlled by the US military, and it has a great security risk to our country; theother part is BDⅠ timing products self-developed by our country, however, the accuracy andcompleteness of the signal coverage also requires a large degree of improvement.To ensure the high-precision of the time reference of test instrument effectively, underthe premise of precision time reference test instrument module cannot be able to completelydivorce from the dependent on GPS timing system, we proposed a demonstration programthat can be used to dual high-precision timing technology of BDⅡ and GPS timing system ofprecision time reference measurement, which will not only eliminate the potential safetyproblems of GPS, but also solve the problem that it cannot complete time service inexceptional circumstances. The key technical of the paper started from the error sourcesaffecting the accuracy of timing, and analyzed it combining with the error related to satellites,the error of signal propagation, and errors related to receivers, the three types of error sources,and proposed the correction algorithm model of relevant errors, also proposed the switchingprinciple of Satellite sources of Dual-mode timing technologies and improvement programsof1PPS. Finally, we applied the proposed algorithm models and improvement programs intothe timing system, and completed the relevant interface communication circuit design andother peripheral circuit design combining with the main control unit, and achieved the designof hardware and software dual-mode timing system of BD2+GPS. The user can achieve the results after preferred with using the timing system, and increased the high-precision oftiming further.Finally, by testing the related function of the output of time information and1PPS of thetiming system, we analyzed results of the measured data by software, and concluded that thestandard of the deviation accuracy of the timing system can be less then20ns,which meets thedemand for the accuracy of the1PPS in the timing module of precision time reference testinstrument.