At the transmitting end, a nX1 Multiplexer combines n no of communication signals(channels) into a single communication signal (channel) by dividing a real time communication channel into n no of equal time slots with respect to time,and inserts smples of n no of signals (sampled at same nyquist rate) into those timeslots in round robbin fashion.so that a single communication channel can be efficiently used. Each  signal can be de-multiplexed at the receiving end in the similar way.  

Posted By: Basava