Method and apparatus for transmitting and recieving multiplex tributary signals

An apparatus for transmitting and receiving a plurality of individual tributary signals in multiplex form via a common line, the apparatus including a transmitter having a plurality of synchronize, each operating on a respective individual tributary signal to produce a tributary signal having an adapted rate, and a multiplexer operable to interleave the adapted rate tributary signals within a compound signal, the apparatus further including a receiver having a demultiplexer operable to separate the compound signal into respective tributary signals having an adapted rate and a plurality of desynchronizers, each operating on a respective adapted rate tributary signal to obtain retrieved tributary signals, the apparatus further comprising:

• in the transmitter,
• means for calculating the phase difference between the compound signal and each tributary signal,
• means for coding the phase difference in bit form, and
• means for inserting the bits coding the phase difference into the compound signal;
• and
• in the receiver,
• means for reading out the bits coding the phase difference from the compound signal,
• means for recovering the frequency of the adapted rate tributary signals,
• means for adjusting the phase of the retrieved tributary signals, wherein the phase difference between the compound signal and a tributary signal is calculated using an auxiliary clock, and
• means for calculating a total phase difference, wherein the total phase difference is a function of stuffing information, a phase difference between write and read addresses at a synchronizer at the transmitting end, and a phase difference between write and read addresses at a desynchronizer at the receiving end.

A method of receiving a plurality of individual tributary signals in multiplex form via a common line, the method comprising the steps of:

• receiving, at a receiving end, a compound signal that has a frame structure with a common data rate, the compound signal having been produced from individual tributary signals, each of which has a substantially identical initial frequency, and including a respective phase difference between each tributary signal and the compound signal inserted into the compound signal in the form of respective coded bits, and,
• retrieving, at the receiving end, from the compound signal, each individual tributary signal with its initial frequency,
• wherein at the receiving end, the initial frequency of each tributary signal is recovered from the phase information included in the respective coded bits belonging to the respective tributary signals,
• wherein the phase difference between the compound signal and a tributary signal is calculated using an auxiliary clock and,
• further comprising the step of calculating a total phase difference, wherein the total phase difference is a function of stuffing information, a phase difference between write and read addresses at a synchronizer at the transmitting end, and a phase difference between write and read addresses at a desynchronizer at the receiving end.

An apparatus for processing plurality of individual tributary signals that are received as via a common line as part of a compound signal that was produced by interleaving initial tributary signals having an adapted rate that were developed from independent tributary signals, the compound signal including in bit form the phase difference between the compound signal and each developed tributary signal, the receiver comprising:

• a demultiplexer operable to separate the received compound signal into respective tributary signals having an adapted rate;
• and
• a plurality of desynchronizers, each operating on a respective adapted rate tributary signal to obtain retrieved tributary signals;
• means for reading out the bits coding the phase difference from the compound signal;
• means for recovering the frequency of the adapted rate tributary signals;
• and
• means for adjusting the phase of the retrieved tributary signals;
• wherein the phase difference between the compound signal and a tributary signal is calculated using an auxiliary clock.