August
1999 QUESTION 1 (Compulsory) Total Marks: 20 Marks |
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questions
SUGGESTED SOLUTIONS |
| (a) | What is the chief cause of attenuation in terrestrial microwave? | [1] |
| Rainfall.
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| (b) | What is meant by a full-duplex transmission? | [2] |
| A transmission in
which both stations may transmit to each other simultaneously.Requires 2 separate
channels.
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| (c) | What is the main problem associated with parallel transmission, which prevents its use over long distances. Explain your answer. | [2] |
| Skew: the problem of
bits loosing their relative timing relationship resulting in bits from the same character
arriving at different times.
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| (d) | Give an advantage and a disadvantage of parallel transmission. | [2] |
| Advantage - high data
speed. Disadvantage - because it requires many paths for transmission, this can be very expensive to implement.
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| (e) | What is unit of measurement for signaling rate? | [1] |
| Baud.
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| (f) | What is a repeater? At which later of the OSI model does this device operate? | [2] |
| It is a device that
regenerates the weakened incoming signal to full strength. Physical layer.
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| (g) | What is meant by delay distortion? | [2] |
| Because propagation
velocity varies with frequency, components of a signal arrive at different times.
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| (h) | A particular connection uses 35-pin connector,
with the pins organized in three rows. It uses signal voltages which vary between +2V and
-2V. Could this be an RS-232C connection? Explain why/why not. What are the other features of the RS-232C specifications? |
[8] |
| This doesn't sound
like an RS-232C connection. The connector format is wrong (number of pins, layout). The
voltage signals are wrong. Functional
specifications Procedural specification
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