CEG3185 : Introduction to Computer Networks

SEG3155 : Communication and Networking

Tutorial 4

Assume a data stream id made of ten 0s. Encode this stream using the following encoding schemes. How many changes (vertical line) can you find for each scheme?◦ Unipolar◦ Polar NRZ-L◦ Polar NRZ-I◦ Bipolar AMI◦ Pseudoternary◦ Manchester◦ Differential Manchester◦ B8ZS◦ HDB3

Q1: Coding Techniques

Calculate the bit rate for the given baud rate and type of modulation:◦ 1000 baud, FSK◦ 1000 baud, ASK◦ 1000 baud, 8-PSK◦ 1000 baud, 16-QAM

Q2: Modulation and data rate

Data from an analogue source ranges in value between –1.0 to 1.0 volts. Assume a uniform quantification of 8 bits. What binary values (you may express the values in decimal) correspond to the following source values?◦ 0.91 volts◦ -0.25 volts◦ 0.5 volts ◦ 0.495 volts

Q3: Pulse code modulation (PCM)

Consider the transmission of a voice analog signal (spectrum between 500 Hz and 4000 Hz) with a digital signal using PCM.◦ Assuming samples are quantized using an 8-bit

code, what is the minimum data rate required to transmit the voice signal?

◦ Given M=2 (2 levels in the digital signal), use Nyquists formula to determine the medium bandwith necessary to support the transmission of the signal.

◦ Determine the level of quantizing noise (decibel).

Q4: Quantizing Noise