(a(i))[1]
State what the term digital signal means.
(a(ii))[2]
State the names of components X and Y labelled on Fig. 3.1.
(a(iii))[2]
Describe what the ADC does.
(b(i))[2]
The optic fibre is $84\,\text{km}$ long and has an attenuation per unit length of $0.19\,\text{dB km}^{-1}$. The input power to the optic fibre is $9.7\,\text{mW}$. At the output from the optic fibre, the signal-to-noise ratio is $28\,\text{dB}$. Calculate, in dB, the ratio $$\frac{\text{input power to optic fibre}}{\text{noise power at output of optic fibre}}.$$
(b(ii))[3]
Calculate the noise power at the output from the optic fibre.