Time synchronisation control apparatus and method

Abstract

A local clock network (10, 12) has a reference control unit (16a, 16b) having a reference clock, processing unit and data memory. Coupled to each reference clock (16a, 16b) by a fibre optic cable (20a1-20an and 20b1-20bn) are a plurality of remote stations (22a1-22an and 22b1-22bn), typically clients desiring an accurate clock signal which is precisely and reliably synchronised with the local clock signal of other users within the network or interconnected networks. The user units (22a1-22an and 22b1-22bn) are in the form of a clock indicator unit which provides a clock signal for use by the internal client systems. Each network (10, 12) is a closed loop system between the associated reference station (16a, 16b) and the associated remote user stations (22a, 22b). Each reference station (16a, 16b) determines the latency associated with each remote user station (22a1-22an and 22b1-22bn) and generates an offset appropriate for each user station (22a1-22an and 22b1-22bn). Each reference station (16a, 16b) then generates a specific clock signal for each remote user station (22a1-22an and 22b1-22bn) on the basis of its reference clock signal adjusted by the appropriate user station offset. The local user time clocks are thus precisely synchronised to one another. A plurality of separate networks (10, 12) are synchronised by reference to their local Coordinated Universal Time (UTC) clocks, with one reference station acting as a master station.

Description

technical field [0001] The present invention relates to systems and methods for providing accurate and predictable synchronized clock signals at multiple remote stations. Background technique [0002] In many transactions and processes there is a growing need to be able to obtain an accurate indication of time for measurement and monitoring etc., eg in control situations for commercial and financial transactions. For this purpose, a Central Coordinated Universal Time (UTC) reference managed by the International Bureau of Weights and Measures BIPM was established in France. This reference is used by several metrology laboratories to provide local Coordinated Universal Time (UTC) within their region. Coordinated Universal Time from one UTC provider is used as the time reference in cases where two separate entities wish to synchronize their transactions or work on a common clock. Synchronization of physically separated and unconnected users is performed using GPS (using GPS t...

AI Technical Summary

Problems solved by technology

[0004] Errors in local time clocks caused by the aforementioned delays and weaknesses can cause the local time clocks of separate users to be offset from each other often by as much as 1 millisecond and sometimes by more

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