High-precision satellite-borne time transfer system

Abstract

The relates to a satellite-borne time system, in particular to a high-precision satellite-borne time transfer system. The problems that pulses per second of a positioning system and a crystal oscillator are adopted in a satellite-borne mapping camera and a star sensor for punctuality, as time synchronization precision difference exists, the high target positioning requirement cannot be met are solved. Time reference sources with long-time and short-time stability are combined organically, and the high-precision satellite housekeeping time transfer system based on a simplified white rabbit protocol is constructed, wherein the precision of the system is higher than 0.1 microsecond. According to the frequency multiplication clock generating process, after an atomic clock is acclimatized by the pulses per second output by the positioning system, an output sine clock is converted into square waves, and then debounce and frequency multiplication are carried out; meanwhile, it is ensured that jumping edges of the frequency multiplication clock and the generated GPS pulses per second are in a determined state. All signals take the frequency multiplication clock as the reference, sampling indeterminacy of a previous asynchronous system is avoided, and delay of a transmission path and delay changes caused by temperature correcting and other factors are measured by receiving time information back and forth.

Description

technical field [0001] The invention relates to an on-board time system, in particular to a high-precision on-board time transfer system. Background technique [0002] Today's spaceborne mapping cameras and star sensors use positioning systems (GPS or Beidou) second pulses and crystal oscillators to keep time, and finally obtain the attitude parameters of the satellite at the corresponding shooting time according to the time stamp of the camera image, and the time synchronization accuracy is about 100μs. Can not meet the requirements of high target positioning accuracy. [0003] In the past, the time reference of the small satellite satellite service system used a separate external clock to provide the timing reference. The satellite service center computer broadcasted the whole satellite time through the first-level CAN bus, and the user of the relevant time system received the whole satellite time through the CAN bus. After completing its own time calibration, the synchro...

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