The invention provides a method for
constellation time keeping in a free operation state of a
satellite-borne
atomic clock, and the method comprises the steps: generating an adjustable second time frequency
signal through
frequency synthesis based on a first time frequency
signal outputted by the
satellite-borne
atomic clock; comparing and measuring the
phase difference between the two and sending the
phase difference to an inter-
satellite link; through inter-satellite measurement and interaction, obtaining a
clock error between the second time frequency signals of all satellites, and converting to obtain a
clock error between the first time frequency signals of all satellites; and on the basis, a
clock difference parameter between the
constellation time and the first time-frequency
signal is calculated and converted into a clock difference parameter between the
constellation time and the second time-frequency signal, a frequency adjustment parameter is generated through a
control algorithm, and the second time-frequency signal is controlled to gradually approach the constellation time. The invention further provides a device for constellation time keeping in the free operation state of the satellite-borne
atomic clock. Therefore, the free operation requirement and the irregular
frequency modulation requirement of the satellite-borne atomic clock under the navigation constellation autonomous time keeping scene can be considered, and the constellation autonomous time keeping precision and the user service performance are improved.