Patent ID: 6333940
Filing Date: 2001-12-25
Classification: H04J,H04L,H04Q

Abstract:
A method of demapping a signal from a synchronous transport signal format comprising virtual tributaries and overhead bytes for transmission over optical paths to a digital signal format for transmission over a wire path, comprising the steps of:writing data bytes in a virtual tributary to an elastic store;incrementing the contents of an accumulator at a rate corresponding to the byte rate at which said data bytes are written to said elastic store;reading stored data bytes from said elastic store at a bit rate corresponding to the rate of a digital signal being demapped from said virtual tributary at said elastic store;decrementing the contents of said accumulator at a rate corresponding to said bit rate;determining from the contents of said accumulator a phase error between said virtual tributary and said digital signal being demapped therefrom, said incrementing and decrementing said accumulator at said byte rate and said bit rate, respectively, to improve the differentiation of phase errors due to byte stuffs and phase errors due to bit stuffs; andsupplying said determined phase error to a circuit configured to reduce said phase error.