Design And Implementation Of GPS And Beidou Time Service System Software

With the accelerated pace of modern society life, people propose strictrequirements regarding the accuracy of time in many fields. In defense-related science,technology and industry, the requirements of high-precision time service are morestringent, and the range for weaponry test must have a high-precision time servicesystem. In view of this, this paper design and implementation the satellite time servicesystem. The system is mainly using GPS(Global Position System) satellite timingpattern and is compatible with Beidou timing pattern to achieve the purpose ofhigh-precision timing in the range.When considered the timing scheme, we compared variety of time service modes,and selected GPS timing pattern to be main time service pattern, which has the higherprecision and the mature technology. In consideration of increasing maturitydomestically manufactured Beidou satellite technology, the system is also compatiblewith Beidou timing pattern. We adopted IRIG-B time code to time synchronizationtransfer, as this time code meet the accuracy requirements and the international standardfor compatible with other systems.The paper briefly describes the hardware part of the system design process.Including selecting the GPS receiver chip to meet the appropriate requirements;selecting high-accuracy crystal and designing correction way of crystal frequencyaccuracy; using real-time and parallel processing capabilities field programmable gateentire array (FPGA) as the core processing devices of system, so that to achieve timecode encoding; designing the system circuit board as standard CPCI(CompactPeripheral Component Interconnect) board for satisfying the desired functionalrequirements.The paper focuses on the two parts of the system software design. The first part ismainly for FPGA realizes the design of the IRIG-B (DC) encoding function. The secondpart is the use of MFC(Microsoft Foundation Classes) technology to edit a PC testsoftware for completing the system performance test. In particular, the PC test softwareimplements the following functions: displaying the time derived from the CPCI board;showing the raw data of the GPS receiver and the local current time; completing theCPCI board set.After completing the design of the GPS time service system, test results show that the timing accuracy of this system meets high-precision time service requirements in therange.