4. Three FDM multiplexers are connected as shown below. If each input has a bandwidth of 10 KHz, what is the minimum bandwidth of the output from the second-stage multiplexer? Assume a 500 Hz guard band between channels. PH 5. Design a hierarchical TDM system to multiplex 6 input channels together. Assume each multiplexer (at any level of the hierarchy) can combine, at most, 2 inputs. Sketch your design. (There are several possible designs.)