A telephone channel allows signal transmission in the range 600 to 3,000 Hz. The carrier frequency is taken to be 1,800 Hz.
(a) Show that 2,400 bit/s, 4PSK transmission with raised cosine shaping is possible. Show that the 6 dB bandwidth about the carrier is 1,200 Hz.
(b) 4,800 bits/s are to be transmitted over the same channel. Show that 8PSK, with 50% sinusoidal roll-off, will accommodate the desired date rate. Show that the 6 dB bandwidth about the carrier is now 1,600 Hz.