4.2-6 Two signals $m_{1}(t)$ and $m_{2}(t)$, both band-limited to $5000 \mathrm{~Hz}$, are to be transmitted simultaneously over a channel by the multiplexing scheme shown in Fig. P4.2-6. The signal at point $b$ is the multiplexed signal, which now modulates a carrier of frequency $20,000 \mathrm{~Hz}$. The modulated signal at point $c$ is transmitted over a channel. Figure P4.2-6 272 ANALOG MODULATIONS AND DEMODULATIONS (a) Sketch signal spectra at points $a, b$, and $c$. (b) What must be the bandwidth of the distortionless channel? (c) Design a receiver to recover signals $m_{1}(t)$ and $m_{2}(t)$ from the modulated signal at point $c$.

Public Answer

B3YUZH The First Answerer