We have $4$ different messages, each with a bandwidth of $5$ kHz$.,$ These messages are to be multiplexed using FDM$.$

$1)$ Sketch the spectrum of each message.

$2)$ Sketch the block diagram of the FDM that deals with these messages.

$3)$ Sketch each step of this FDM $($output of each stage$).$

$4)$ Show all details