(a)[1]
State what is meant by the attenuation of a signal.
(b(i))[1]
A transmission cable is $30\,\text{km}$ long. The attenuation per unit length of the cable is $2.4\,\text{dB km}^{-1}$. Calculate, for a signal sent along the cable, the total attenuation, in dB.
(b(ii))[3]
Calculate the ratio of the signal’s input power to its output power.
(c)[1]
Using your answers in (b), suggest why attenuation of transmitted signals is usually quoted in dB.