12. An 8-bit Pulse Code Modulation system is employed in a telephone network having an analog bandwidth of 4KHz. Determine each of the following: a) Sampling rate. b) Bit rate. c) Required bandwidth 13. A one-hour conversation is recorded and stored digitally using Pulse Code Modulation at 8000 samples per second. If each sample is encoded as 8-bits, how many Compact disks (CDs) are required if each CD can take 720 MB? 14. A digital signaling system is required to operate at 9600 bps a) If a signal element encodes a 4-bit word, what is the minimum required bandwidth of the channel? b) Repeat part a) for the case of 8-bit word. 15. Describe briefly the characteristics of the following transmission media. a) Twisted pair. b) Coaxial cable. c) Optical fiber cable. d) Microwaves. 16. Differentiate briefly between Frequency Division Multiplexing and Time Division Multiplexing