Download In your answer you would identify and expl

Section A
1.
Identify and briefly explain four types of signal impairment.
(8 marks)
In your answer you would identify and explain the source and effects of any four of the
following types of signal impairment: Attenuation, attenuation distortion, Delay
distortion and/or any of the four types of noise including Crosstalk, Impulse noise,
Thermal noise and inter-modulation noise. You would also explain how these might be
addressed if at all.
2.
Explain the purpose of the voltage transitions occurring during the bit interval when
using Manchester encoding.
(8 marks)
Explain that the transition is used to encode the data and to convey timing. You would
also explain that transitions at the start of the interval are ignored and serve no purpose
for this encoding technique. A diagram would also be useful for explanation purposes.
Section B
3.
Explain the concept of FDM multiplexing. In your answer illustrate the resultant
waveform in the frequency domain and explain how this technique might be used in
the transmission of telephony services.
(15 marks)
Here you are asked specifically for a diagram; so include a fully-labelled diagram. It
would also be very useful to include a diagram of the MUX device itself. This will assist
you in explaining the operation of the technique and, if time is running out for writing
detailed text, it would demonstrate a deeper understanding and likely score you extra
marks. Recall that these devices are used to carry multiple communications along a
single transmission path. For telephony services it means that multiple conversations can
be conveyed simultaneously. It would be efficient if you could use the earlier diagram of
the waveform to illustrate this concept. You would have to explain how the individual
conversations are separated on the line.
4.
Explain the operation of Sliding-windows Flow Control between two stations A
and B where each station has three frames to send. Illustrate the status of the
memory buffers on each station after each transmission. Choose you own
transmission scenarios to illustrate keys concepts associated with the technique.
Once again a detailed diagram is required. Think through the operation of the technique
and in your chosen scenarios make sure you cover the key concepts such as a lost
frame/ack, time-out and busy condition. These were covered in detail in class. In this
type of question the diagram is really important so pay particular attention to the detail.
Any text should support the diagram. Show the frames traversing the line and show the
status of the buffers after each transmission/reception.
(15 marks)