(as letters) abbr. Digital multiplexing in which two or more apparently simultaneous channels are derived from a given frequency spectrum or bitstream by interleaving pulses representing bits from different channels. Short for Time-Division Multiplexing. In some TDM systems, successive pulses represent bits from successive channels (e.g., voice channels in a T1 system). In other systems, different channels take turns using the channels for a group of successive pulse times (a “time slot”).