Method of multiplexing digital signals and apparatus therefor

Abstract

A high speed digital signal multiplexing method and apparatus are provided wherein a plurality of first higher bit rate transmission frames are provided, each first higher bit rate transmission frame being multiplexed therein with lower bit rate signals in an n-byte (n is an integer) interleave manner, and the lower bit rate signals are selectively derived from the plurality of first higher bit rate transmission frames and multiplexed into a second higher bit rate transmission frame. When a phase conflict is detected among the derived lower bit rate signals, all the data columns of at least one of the derived lower bit rate signals are given a predetermined delay by means of a shift register, and the derived signals are multiplexed into the second higher bit rate transmission frame. When a first higher bit rate transmission frame asynchronous with the system frame is detected, a pointer is derived which pointer represents a predetermined information unit within the derived lower bit rate signal. The derived pointer is inserted into a time slot corresponding to the frame pattern position of the second higher bit rate transmission frame for the lower bit rate signal. Thereafter, the derived signals are multiplexed.