Automatic time synchronizing method on satellite

A time system and time difference technology, which is applied in transmission systems, radio transmission systems, communications between multiple stations, etc., can solve the problem of weak accurate tracking ability of satellite-to-ground time difference, observation error of time difference, and inability to consider the random variation of the clock, etc. problems to ensure accuracy and reduce workload

Active Publication Date: 2009-03-11
AEROSPACE DONGFANGHONG SATELLITE
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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 metho

Method used

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  • Automatic time synchronizing method on satellite
  • Automatic time synchronizing method on satellite
  • Automatic time synchronizing method on satellite

Examples

Experimental program
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Example Embodiment

[0125] Example 1

[0126] Use the ground station and the inter-satellite link to realize the autonomous synchronization processing between the on-board clock of each satellite constellation (24-satellite Walker constellation) and the ground system clock (for example, the goal is to always control the second pulse synchronization error of the on-board clock and the ground system clock In the range of 1us.) The on-board clock uses a typical high-stability crystal oscillator QZ clock, and the ground uses a CS clock. In each time system period (assuming 5s), the ground station measures the time difference between the transit satellite clock and the ground system clock (assuming accuracy is 30ns), and the inter-satellite time difference between adjacent satellites is measured through the inter-satellite link (assuming accuracy) Is 10ns). Based on the uploaded satellite-to-ground time difference observation data of transit satellites, combined with inter-satellite time measurement data,...

Example Embodiment

[0138] Example 2

[0139] The GPS navigation system is used to realize the autonomous synchronization processing between the on-board clock of each satellite constellation (24-satellite Walker constellation) and the ground system clock (for example, the synchronization error of the second pulse between the on-board clock and the ground system clock is always controlled within the range of 1 us). The on-board clock uses a typical QZ clock, and the ground uses a CS clock. In each time period (assuming 5s), the ground station uses the GPS navigation system to time the system time difference observation sequence of the ground system clock relative to the navigation system clock (assuming the timing accuracy is 100ns, but the actual accuracy is higher than this!), An on-ground EKF filter similar to the on-board EKF filter, based on this type of observation data, gives a posteriori estimate of the time difference, frequency difference and aging rate of the system clock, and passes throu...

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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...

Claims

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Application Information

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IPC IPC(8): H04B7/185H04B7/26
Inventor 黄琳马文杰
Owner AEROSPACE DONGFANGHONG SATELLITE
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