Attenuation

Attenuation is a measure of how much a signal weakens as it travels through a medium, Attenuation is a contributing factor to why cable designs must specify limits in the lengths of cable runs. When signal strength falls below certain limits, the electronic equipment that receives the signal can experience difIculty isolating the original signal from the noise present in all electronic transmissions. The effect is exactly like trying to tune in distant radio signals. Even if you can lock on to the  signal on your radio, the sound generally still contains more noise than the sound for a local radio station. As mentioned in the previous chapters, repeaters are used to regenerate signals; hence one solution to deal with attenuation is to add a repeater.