Design And Implementation Of Network Time Synchronization Server Based On Beidou

Several time-service technologies,such as short-wave time-service,long-wave time-service,radio broadcast time-service and digital television time-service technologies,have been invented in order to meet the need of daily production and life in different regions and industries.However,with the progress of science and technology,many precision instruments have been introduced into transportation,electricity,schools,government agencies,the army,etc.These precision instruments put forward higher requirement for time synchronization.To provide precise time information for these instruments,a time-service method is provided by using timing function of satellite navigation system in this paper.At present,there are four kinds of navigation systems in the world,Global Positioning System of America(GPS),Global Navigation Satellite System of Russia(GLONASS),Galileo Satellite Navigation System of Europe(Galileo)and Bei Do u Satellite Navigation System of C hina(BDS).Beidou Satellite Navigation Sys tem can provide high precise and reliable time service for all kinds of users all-day and all-time globally.In this paper,BDS is chosen as time source.Time synchronization of time display screen in office buildings can be achieved by the serial port commanding the PC which controls the display screen,the display control software reading the time from the PC,and then pushing it to the display screen.This method is suitable for places without networks.The power plant control system can obtain the time information of day,hour,minute and second from IRIG-B code,and then calibrate the time in the system,so as to achieve time synchronization in all equipments.Daily office computers can use NTP timing.file generation time and mail delivery time can be recorded accurately so as to access easily.By investigating the existing Serial time-service,IRIG-B code and NTP time-service,it is found that most of devices are implemented by FPGA+DSP+parallel DAC or FPGA+ARM+parallel DAC.This method has many deficiencies,such as the interconnections among the chips,the complex PCB design,the large area,the high processing cost,and the single time-serve.In this paper,we use ZYNQ device and serial DAC chip,data exchange are implemented in chip,which avoids more interconnections between chips.Besides,simple PCB design and small area are help to small-scale design,upgrade and maintenance of the machine.ZYNQ device is mainly composed of PS(processing system)and PL(programmable logic).This paper mainly makes breakthroughs in the following four aspects:1)Study on the DMA(Direct Memory Access)data transmission between PL and PS,and repalcing the data transmission between SRIO chips in the scheme of FPGA+DSP.2)Study on the AXI data transmission between PL and PS,AXI data transmission inside the chip,and repalcing the chip selection signal,read-write enabling signal,data bus and address bus of data transmission between chips in the scheme of FPGA+DSP.3)Study on the data transmission method between ZYNQ device and serial DAC,usually using 204 B protocol and the line rate of 12.5 GHz.Parallel DAC chips usually choose 8 bits,PCB wiring requires 8 wires,while 16 bits serial DAC chips only need 2 diffe rential signal lines.4)Study on the fibre-optical time transmission,which is suitable for the occasion where the time-service equipment and the time-service equipment are more than 1 kilometer apart.Based on the analysis of serial time-service,IRIG-B code time-service and NTP time-service,each sub-module has been designed and PC software of serial time-service and NTP time-service have been compiled in chapters.Finally,the network time synchronization server is tested.1PPS,IRIG-B code,serial time-service,NTP time-service are normal,the results reach the design purposes.The network time synchronization server designed in this paper adopted new devices and new methods,with variety time-service modes and novel design.