QUESTION ONE (30 Marks)
a). Differentiate between the following terminologies as used in data communication.
i. analog data and digital data. (2 marks)
ii. Analog signal and digital signal (2 marks)
iii. Period and frequency (2 marks)
iv. Data rate and baud rate (2 marks)
b). One of the major functions of the physical layer is to move data in the form of electromagnetic signals across a transmission medium. Explain why? (3 marks)
c). What is a composite signal according to Fourier analysis? (4 marks)
d). Discuss the following line encoding schemes.
i. Unipolar scheme (2 marks)
ii. Non-Return-Zero (NRZ- I) (2 marks)
iii. Polar Schemes (2 marks)
iv. Non-Return-Zero (NRZ- L) (2 marks)
e). An analog signal carries 4 bits per signal element. If 1000 signal elements are sent per second, find the bit rate. (2 marks)
f). Discuss the principle and applications of an omnidirectional antenna.(2 marks)
QUESTION TWO (20 Marks)
a). A very important consideration in data communications is how fast we can send data, in bits per second over a channel. Identify three (3) factors that data rate depends on.(3 marks)
b). Discus the listed theoretical formulas:
i. Noiseless channel: Nyquist Bit Rate (4 marks)
ii. Noisy channel: Shannon capacity (4 marks)
c). We need to send 265 kbps over a noiseless channel with a bandwidth of 20 kHz. How many signal levels do we need? 3 marks)
d). We can calculate the theoretical highest bit rate of a regular telephone line. A telephone line normally has a bandwidth of 3000 Hz (300 to 3300 Hz) assigned for data communications. The signal-to-noise ratio is usually 3162. Calculate the capacity of the channel. (3 marks)
e). Identify any three characteristics of microwave propagation. (3 marks)
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