Method and system for using synchronous digital hierarchy (SDH) to realize high-accuracy time synchronization

Abstract

The invention provides a system for using an SDH optical transmission system to realize high-accuracy time synchronization and a method thereof. The technical scheme overcome the defect of inaccurate transmission time delay measurement in a traditional method, realize the automatic accurate measurement of the transmission delay of a time signal and use the high-accuracy time delay measurement value to modify the phase of the time signal, thus realizing the high-accuracy time synchronization. Proved by experimental result, on two SDH network elements connected by a 50-kilometer optical fiber, the invention can be adopted to automatically measure the time relay of a transmission link and modify the phase of the time signal, and the time synchronization error is more accurate than 10ns, manual presetting of a time delay compensation value is not needed. Therefore, the method is greatly superior to the traditional method.

Description

technical field [0001] The present invention relates to a time synchronization system and a method thereof, in particular to a system and a method for realizing high-precision time synchronization by using an SDH (Synchronous Digital Hierarchy) optical transmission system, and belongs to the technical field of time synchronization. Background technique [0002] Time synchronization refers to the use of a method to make clocks in different geographical locations consistent with a reference clock with high precision in terms of frequency, phase and time. Accurate time synchronization plays an important role in scientific research, national economy and even military activities. There are several ways to achieve time synchronization, with varying degrees of accuracy. [0003] At present, navigation satellite systems (GPS, GLONASS, Beidou, etc.) are widely used to achieve time synchronization, which has the advantages of high accuracy and global coverage, and can be used in many...

AI Technical Summary

Problems solved by technology

In the case of only two SDH network elements, if the time delay τ value is not manually corrected, the time synchronization accuracy of the above method can only reach about tens of microseconds, and with the increase of the number of SDH network elements on the transmission link , the error will further expand

If the delay τ value is manually corrected, although the error can be reduced to a certain extent, as long as the state of the transmission link changes, the transmission delay will change, and the preset delay correction value will become invalid.

Therefore, the above two methods have not fundamentally solved the problem of accurately measuring the transmission delay, and there are certain defects and large errors.

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