December
1999 QUESTION 1 (Compulsory) Total Marks: 30 Marks |
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questions
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| (a) | Explain the terms bit rate
and baud .In what circumstances will they take on different values?
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[2] |
| (b) | What is meant by full-duplex
communications?Provide a suitable example. |
[2] |
| (c) | With the aid of a diagram,describe
frequency division multiplexing . |
[3] |
| (d) | What are the advantages of
using fibre optics? |
[2] |
| (e) | What are the factors that
cause attenuation in fibre optics? |
[2] |
| (f) | Why is message switching not
suitable for real-time traffic? |
[2] |
| (g) | What is meant by noise in
the context of data communications?Name and describe one type of noise. |
[3] |
| (h) |
Explain one encryption technique,using
an appropriate example. |
[3] |
| (i) | Name and briefly explain the
major elements of a LAN. |
[4] |
| (j) | What are the disadvantages
of using a ring topology for a LAN? |
[2] |
| (k) | The data-link layer consists
of two sub-layers.Name those layers. |
[2] |
| (l) |
A particular modem is running at
9 600 baud.It modulates signals using both amplitude and phase modulation.The
phase shifts are at 0,90,180,and 270 degrees, with two different amplitude
levels per phase shift.How many bits per second can it transmit?Show
all workings and assumptions you make. |
[3] |