| (a) |
What is noise in the context of data
communications. Why is noise a problem? |
[3] |
| (b) |
What is attenuation? Why is it undesirable?
Explain the chief cause of attenuation in terrestrial microwave communications. |
[4] |
| (c) |
Some types of noise can be overcome by careful
design. However, there is one type of noise which is unavoidable. What is this type of
noise called? Explain why it is unavoidable. |
[3] |
| (d) |
What is meant by delay distortion and how is
this problem overcome? |
[2] |
| (e) |
The following bytes have been received. They are
encoded using even parity. Which ones have been corrupted by communication noise? 
|
[6] |
|
Suppose that every fourth byte is inserted as an
LRC (longitudinal redundancy check) check character (with even parity). What was the
original 6-byte message? What assumptions have you made? |
|
| (f) |
What is the transmission efficiency of the
message transmission scheme used in part (e)? |
[2] |