Patent attributes
A packet switched communications system and method for transmitting synchronous data from a source module (4) to a terminating module (8) over a network comprising plurality of modules (4, 5, 7, 8) interconnected via transmission links (2, 6, 9). Each module operates with a clock of nominal frequency that is not synchronized with the clocks of the other module(s) and has a single input and one or more outputs. The method includes determining the phase difference between the input clock and the output clock of each module, and transmitting the phase difference to the terminating module (8) in the network. The received accumulated phase difference at the terminating module (8) is used to lock the output clock at the terminating module to the input clock at the source module.