(a(i))[1]
Suggest one benefit of a wider bandwidth.
(a(ii))[2]
State the meaning of crosstalking.
(b)[2]
In telecommunications, $1.0\,\text{mW}$ is taken as the reference power. Powers quoted in $\text{dB}$ relative to this reference are measured in $\text{dBm}$. Show that a signal power of $13\,\text{dBm}$ is equal to $20\,\text{mW}$.
(c)[2]
A signal with input power $20\,\text{mW}$ travels along an optic fibre over a continuous distance of $45\,\text{km}$. The optic fibre has an attenuation per unit length of $0.18\,\text{dB km}^{-1}$. Calculate the output power $P$ from the optic fibre.