3f Optical Communication ***

Question 0

Describe three advantages for the wedding outfitter of using fibre optic cable to connect the two buildings. (6 marks)

Answer 0

 greater capacity (1) more data can be exchanged
simultaneously (1)
 transmission rates (1) higher volume of data per second (1)
 less signal degradation (1) data can travel greater distances
without amplification (1)
 not susceptible to electrical interference (1) better quality of
data transmission/less errors (1)
 security (1) less difficult to tap in to (1) doesn’t leak light (1)
 carries digital signals (1) no need for signal conversion (1) [6]

Question 1

Describe three disadvantages of using fibre optic cable to connect two buildings for a small business. (6 marks)

Answer 1

One mark for point, one for expansion eg:
 cost of cable is more expensive (1) compared to wire
media (1)
 network portion needs to be down (1) if new nodes are to
be spliced in (1)
 breakage/damage to cable (1) entire cable needs re-laying
(1)
 initial set up cost (1) electronic signals require conversion
(1) by a source and a receiver (1) at both ends of
transmission (1)
 optical regenerators/laser amplifiers needed (1) impurities
in the glass and the wavelength used cause the signal to
degrade over large distances (1)
 physical disruption (1) if cable needs to be housed
underground (1).
Max two points per disadvantage
[6]

Question 2

Describe three disadvantages, for the business, of using lasers to connect the LANs in the
salons together. (6 marks)

Answer 2

 direct line-of-sight required (1) laser beam cannot be bent
around any intervening building / obstacle (1)
 atmospheric changes (e.g rain, smoke and fog) (1) can affect
quality of signal (1)
 both ends of communication need the hardware (1) the cost
of set up can be inhibiting (1)