Consider two $4-$to$-1$ TDMs$,$ a synchronous TDM and an asynchronous TDM$.$

Both multiplexers receive identical data in the same time on their input lines

where the data arrives at a speed of $10$Mb$/$s on each line. Let Y $(4$ bits long$)$ and

N $(4$ bits long$)$ represent the presence and non$-$presence of data, respectively, so

that the input lines$$ data patterns are: Line $1($YNYN$),$ Line $2($NNYN$),$ Line

$3($NYNY$),$ and Line $4($YNNY$).$ The synchronous TDM requires only one $4-$bit

control channel on its frame while the asynchronous TDM requires one $4-$bit control channel for each frame and an additional $4-$bit control channel per channel.