The communication and cooperation of multiple equipment and instruments are widely used in real-time measurement, high-speed object measurement and control, detection and other fields. This paper briefly introduces remote clock synchronization technology.

The multi machine synchronous clock participating in cooperation is classified as host and slave. Because of the multi machine location decentralization, wireless communication becomes the only means of communication, so each device is equipped with an independent clock source, and the low error rate index of the output data of the joint operation sets higher requirements for the clock synchronization between multiple computers, so that the relative error of the clock error is higher order and negligible in the data calculation process.

In engineering applications, the relative difference of the whole second edge often needs to be controlled within sub microsecond or even tens of nanoseconds. At the same time, the jitter noise of the clock must be strictly restricted.

At present, the clock synchronization between multi computers at home and abroad is based on the main base station broadcast, and the sub station receives and analyzes the satellite navigation message, mainly through the timing synchronization of the mobile communication network, and directly obtains the edge synchronization of the clock pulse by edge technology. However, the synchronization accuracy of these methods sometimes fails to meet the requirements of joint measurement or measurement and control. High precision atomic clock wireless calibration time is expensive, which limits its popularization and application in surveying and mapping and industrial fields.

In order to achieve higher synchronization accuracy and control cost and simplify design, a new clock synchronization method based on satellite timing is proposed. Using the clock data block and carrier signal transmitted by the navigation satellite, the high-precision second pulse is output by combining the PLL technology, and the accumulated error of the high stable crystal oscillator is modified on demand according to the characteristic of the long-term accumulation error limit approaching zero. Commonly used product models recommend SYN2401 synchronous clock and SYN2407F slave clock module or module SYN2306C type.

In the process of application, the satellite numbers of different stations are the same in most of the time. The triggering signal source will switch in the short period of triggering boundary conditions, resulting in the increase of the clock edge deviation of different receiving points, and the priority of the signal source can be changed by the point to point or broadcast mode, and the time of the clock mutation is shortened. Of course, even with different star sources, the clock error can usually be controlled within tens of ns or even a few ns. Therefore, the accuracy of clock synchronization can still meet the requirements in most cases.

The error characteristics of satellite clock and crystal clock are complementary: the clock clock error of satellite clock obeys normal distribution, and the random error is large and the accumulated error is small. Compared with the international standard time, the clock time offset of crystal clock is very small, and the offset is relatively stable, and its random error is small and cumulative error is large. According to the complementary characteristics of the error between the satellite clock and the crystal clock, the advantages of the two algorithms can be combined by mathematical algorithm or digital circuit technology, and then the high-precision synchronous time service clock can be obtained.

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