14. A satellite allocates a frequency band from 2000 MHz to 2040 MHz for transmission of digitized audio signals. Multiple audio signals, each made up of 2 stereo channels with a highest frequency of (N+5) kHz, must be sampled at 1.6x the minimum alias-free rate and digitized with 10-bit accuracy. The resulting PCM signals must then be combined by TDM and transmitted from the satellite using M-QAM modulation of a single carrier. (N=13) (a) What bit rate is required for a single audio signal? (b) If minimum-bandwidth pulses are used to carry the data, what is the maximum symbol rate allowed by the allocated bandwidth? (c) If 64-QAM format is used, what is the maximum possible bit rate? (d) If 64-QAM format is used, what is the largest number of audio signals that can be supported? (e) If noise is found to create excessive bit errors, choose a format other than 64-QAM that should do better, and find the largest number of audio signals that can be sent with your chosen format.