A simple form of data multiplexer that concentrates traffic from multiple low speed asynchronous devices onto a single high speed synchronous circuit, usually by time division multiplexing (TDM). In a simple concentrator, the total speed of the low speed incoming channels is equal to or less than the speed of the high speed outgoing circuit, so the maximum incoming load placed on the concentrator never exceeds the capacity of the outgoing circuit. In a more sophisticated concentrator, the incoming traffic load may exceed the capacity of the outgoing circuit, with buffers serving to store the excess data traffic for short periods of time until capacity is available on the outgoing circuit.At this more sophisticated level, a concentrator is a relatively unsophisticated statistical time division multiplexer (STDM). See also buffer, multiplexer, STDM, and TDM.