Method for communicating block coded digital data with associated synchronization/control data

A method for communicating block coded digital data and associated overhead data comprising the steps of:

• providing a data stream having a succession of coded blocks, each block containing an integer number N of symbols wherein an integer number M of said symbols comprise information to be transmitted and the remaining N-M of said symbols comprise error correcting data, the ratio M/N comprising a first information rate;
• dividing the coded blocks in said data stream into a succession of frames, each frame comprising F of said coded blocks;
• and
• adding P frame overhead symbol(s) for each of said frames, said frame overhead symbols containing data necessary to provide a function at a receiver;
• wherein:
• (i) the addition of said frame overhead symbols effectively lowers said first information rate to a second information rate M'/N', where M/N=(M'+b)/(N'+b) and b is an integer chosen to provide said second information rate at a desired value,
• (ii) N.ltoreq.2.sup.n +1, where n is the number of bits in each of said symbols,
• (iii) F=M'P/(N-M)b, and
• (iv) P is an integer chosen to render F an integer.