(a) "Pulse Code Modulation (PCM), as used in telephony, samples a signal at 8 kHz using 256 quantization levels".
i. Outline how this scheme works with the help of sketches and, by reference to the Nyquist's Sampling Theorem, illustrate how the sampling rate was chosen.
ii. Determine the SNR in dB for the quantization error of this PCM setup.
iii. Determine the data rate achievable.
(b) Give three advantages that digital transmission has over analogue transmission.
(c) Explain three types of communication impairments that you are familiar with and, with reference to a standard communication model, state where the above-mentioned impairments generally occur.