Two signals m₁​(t) and m₂​(t), both band-limited to 5000 Hz, are tobe transmitted simultaneously over a channel by the multiplexing scheme shown in Fig. P4.2-8. The signal at point b is the multiplexed signal, which now modulates a carrier of frequency 20,000 Hz. The modulated signal at point c is transmitted over a channel. (a) Sketch signal spectra at points a,b, and c.