基于时间触发以太网的星载时频统一系统OA

Satellite time-frequency unified system can realize the time-frequency consistency between satellite-ground,inter-satellite and intra-satellite systems.According to the different requirements of each satellite sys-tem and onboard terminal for time synchronization accuracy,three types of time synchronization accuracy inter-vals,including high precision,general precision and coarse precision,as well as typical application scenarios of different types of synchronization accuracy requirements,are proposed.The time synchronization with different accuracy requirements is met by the combination of satellite time-frequency reference time synchronization,on-board terminal time synchronization and local clock punctuality.With the continuous increase of the types of data transmission services and interaction frequency of the satellite network,as well as the number of high-pre-cision time synchronization onboard terminals,the satellite data transmission network is constructed by time-triggered Ethernet,and the global synchronization clock is constructed and maintained by using the AS6802 time synchronization protocol.After the time synchronization is completed,the end system can provide synchro-nization pulses with an accuracy of better than 500 ns for the onboard terminal to meet the requirements of high-precision time synchronization.The time-triggered message is based on the AS6802 time synchronization to ensure that the end system and switch process the message in a high-precision aligned time window,which a-chieves a message transmission delay of about 100 μs and a message jitter control of about 10～20 μs,and meet the time synchronization requirements of most onboard terminals without adding additional software and hardware overhead.