Automatic time synchronizing method on satellite

Abstract

The invention relates to an on-board automatic time accounting method which endows with the long and high accuracy punctuality performance and the automatic phase modulation performance of the prior time management unit. A time difference processor uses the latest filtration result estimated in real time by a time difference EKF filter to periodically replace the original stored variable estimation value by the time difference observed quantity; on the one hand, the time difference processor broadcasts the forecast time difference for a user, and judges whether the forecast time difference at the current time enters the phase modulation section or not, if entering the phase modulation section, a second pulse generator is driven to perform the corresponding phase modulation according to the calculated phase modulation quantity through calculating the phase modulation quantity and the name phase modulation residual error, and uses the name phase modulation residual error to replace the start forecast time difference quantity and the time difference prior estimation value in an on-board time difference forecast model, thereby the on-board automatic time unification is realized. The invention can lower the degree of dependence to a land station, helps to reduce the requirements of the on-board clock performance, saves the investment and the maintenance costs of a constellation system, and improves the reliability and the safety of the constellation system.

Description

technical field [0001] The invention relates to an on-board time system method, in particular to an autonomous synchronization method for an on-board clock and a ground system clock, and is compatible with traditional ground station intervention time system methods, and is especially suitable for autonomous time system processing of satellite constellation systems. Background technique [0002] The output frequency of the clock (or frequency source) has main error factors such as frequency calibration deviation (called frequency difference or accuracy), aging phenomenon and random noise. Therefore, various pulse signals synthesized according to the accumulation of frequency source oscillation times ( represents a time interval) and the corresponding ideal value always has some degree of phase deviation (or time difference), and as time goes by, this phase deviation becomes larger and larger. In order to realize some interactive functions, the phases between the pulses output...

AI Technical Summary

Problems solved by technology

The above two types of tracking methods have their own advantages and disadvantages: the former is limited by the observation area and time (for example, the distribution of ground stations is limited; the frequency of satellite-to-earth measurement is limited), and there are observation errors in time-difference observations, etc.; the latter Unable to consider the random changing part of the clock (random noise), heavily dependent on the estimation accuracy of model variables (initial forecast time difference, frequency difference and aging rate), and the long-term time difference forecast error will grow rapidly at any time

[0004] The main disadvantage of the time statistics method based on the intervention of the ground station is: the ability to accurately track the time difference between the satellite and the ground is weak, resulting in high requirements for hardware performance and heavily relying on the intervention of the ground station

However, according to the current data, the system also does not have the capability of autonomous physical synchronization, and as a navigation system, there is no need for precise satellite-to-ground time synchronization.

[0008] The on-board time system method based on ground station control will cause a considerable workload and high cost burden on the ground station for a constellation system with dozens of satellites

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