US 7,602,811 B2
	Synchronization in a communication system
John David Porter, Gt. Shelford (United Kingdom); and Benedict Russell Freeman, Cambridge (United Kingdom)
Assigned to Cambridge Broadband Limited, Cambridge (United Kingdom)
Appl. No. 10/510,406 PCT Filed Apr. 03, 2003, PCT No. PCT/GB03/01477 § 371(c)(1), (2), (4) Date Apr. 01, 2005, PCT Pub. No. WO03/088595, PCT Pub. Date Oct. 23, 2003.
Claims priority of application No. 0208374.9 (GB), filed on Apr. 11, 2002.
Prior Publication US 2005/0175037 A1, Aug. 11, 2005
Int. Cl. H04J 3/06 (2006.01)

U.S. Cl. 370—503  [375/356]

20 Claims

1. A packet switched communications system for transmitting synchronous data from a source module to a terminating module over a network, the network comprising plurality of modules interconnected via transmission links, each module the network having a clock of nominal frequency that is not synchronized with the clocks of the other module(s) in the network and having a single input and one or more outputs where all the outputs of each module are phase locked to each other but are not synchronized with respect to the input, means for determining an accumulated phase difference between an input clock and an output clock of each module, means for transmitting the accumulated phase difference to the terminating module, and means for utilizing the received accumulated phase difference at the terminating module to lock an output clock at the terminating module to an input clock at the source module.