Method and apparatus for performing format conversion between bit streams

Apparatus, in a digital communication system including a timer for providing frame synchronization and clock signals, for converting a first serial bit stream, with sub-rate circuit data formatted according to a first predetermined protocol embedded therein, into a second serial bit stream, with said sub-rate circuit data formatted in accordance with a second predetermined protocol embedded therein, comprising:

• (a) means, coupled to said timer, for generating a current address signal to indicate channel and frame number for the information being input by way of said first serial bit stream;
• (b) synchronization and index generation means, for detecting the starting postion of frames and multiframes in order to create an address offset into an aligned data memory used to collect and store sub-rate circuit information;
• (c) aligned data memory means coupled to said synchronization and index generator means, for aligning and storing sub-rate circuit data therein;
• (d) format conversion module means, including a predefined bit map driven by the aforesaid channel and frame number, for assembling a frame of reformatted sub-rate circuit information, reformatted according to said second predefined protocol, and for embedding said frame of reformatted information in said second bit stream;
• and
• (e) means for outputting said second serial bit stream with the reformatted sub-rate circuit data embedded therein.

A method, for use in a digital communication system that carries data in a plurality of sub-rate data formats, for converting a first serial bit stream, with data embedded therein in accordance with a first predefined sub-rate data format, into a second bit stream, with data embedded therein in accordance with a second predefined sub-rate data format, comprising the steps of:

• (a) locating the sub-rate data formatted in accordance with said predefined sub-rate data format, embedded in said first serial bit stream;
• (b) extracting the formatted sub-rate data so located and storing same in an aligned fashion in a storage means;
• and
• (c) constructing said serial bit stream from the stored aligned data utilizing a bit map designed to organize said second serial bit stream in accordance with said second predefined sub-rate data format.