Study Of Beidou And GPS Timing System

In the modern informatization society, the use of high-precision clock is very important in the electric, communication, rail-way and aviation field. For satisfied the demand of temporal accuracy, the GPS time-service has been used in general. The advantages of GPS time service are high-precision, good stability and wide overlap ranges, etc. But the GPS is developed by American military, since the effect of ideology and political elements the, there are some issues of safety and stability by using the GPS clock as the unique time source."Beidou I"is the satellite navigation system which developed on our country's own. The time service of it is better that GPS. But the disadvantages of that is the amount of satellite is lack and not as stable as GPS. According to this situation, we choose to use Beidou and GPS as dual active to give the clock service. It can receive the signal both from Beidou and GPS in the same time. It uses the advance time-control processing algorithm to achieve the double time sources smart switching. By using of this method, the safety issues from GPS and the stability issue from Beidou can both be solved. In the meantime, consider about the Beidou and GPS can lose locked in the same time, this system also have a timekeeping function module. So even the Beidou and GPS both losing locked in the same time, the time service system still can maintain the stability and precision for a while.In the process of timing, time-synchronization is an important standard which can decide the quality of timing. This thesis has analyzed the factors which effective the time-synchronization precision from both software and hardware. Using the micro processor as the core, combined with the smallest cost hardware circuit, using the design method of combination of the software and the hardware can save the cost of design and also makes the modules relative independent. First of all this thesis introduced the timing system structure figure as a whole. Then this thesis introduced the modules design in the different chapters. This thesis discussed the design methods, specific realization process, hardware design, software design, environment results and error analysis in detail. It has been proved that this system is safe, stable and high-precision of timing by the verification of engineering process. It is satisfied of demands of Chinese timing system since the precision of time-synchronization is in 100ns and the signal step change is in 80ns.