For high precision time synchronization demands of long term on orbit spacecraft

an autonomous high precision time management system is proposed

which combines Beidou navigation equipment clock generator and frequency synthesizer clock generator. Two clock generators can autonomously switch by states of navigation and localization

it eliminates error accumulation effect of frequency clock generator system and solves the problem for time precision falling dramatically when Beidou navigation equipment is unable to be located. By building error model for system taking an real application in spacecraft for example

to compute and analyze

which indicates that precision of the system time synchronization is prior to 37. 8 μs. The result can be a reference for subsequent design of high precision time management system spacecraft.