Cable television relies on optic fibres to carry signals. Suggest four benefits of optic fibres compared with coaxial cables for data transmission.
Radiation with wavelength $1310\,\text{nm}$ is often chosen for optic fibre communication instead of visible light. State the part of the electromagnetic spectrum that contains radiation of wavelength $1310\,\text{nm}$.
Suggest the reason this radiation is chosen instead of visible light.
An optic fibre has an attenuation per unit length of $0.2\,\text{dB km}^{-1}$. A signal travels through the optic fibre over a length of $30\,\text{km}$ to a receiver. The noise power at the receiver is $9.3\,\mu\text{W}$. The minimum acceptable signal-to-noise ratio at the receiver is $26\,\text{dB}$. Calculate the minimum signal power at the receiver.
Calculate the minimum input signal power to the optic fibre.