|  | 4.3 | Basics of Signals and Noise in Communications Systems
| 4.3.5 | Network attenuation

Attenuation is the loss of signal strength, for example, when cables exceed a maximum length. This means that a 1 bit voltage signal loses amplitude as energy passes from the signal to the cable. While choosing materials carefully, (e.g. using copper instead of carbon), and geometry (the shape and positioning of the wires) can reduce electrical attenuation. Some loss is always unavoidable when electrical resistance is present. Attenuation also happens to optical signals; the optical fiber absorbs and scatters some of the light energy as the light pulse, 1 bit, travels down the fiber. This can be minimized by the wavelength, or color, of the light that you choose. This can also be minimized by whether or not you use single mode or multi-mode fiber, and by the actual glass that is used for the fiber. Even with these choices, some signal loss is unavoidable.

Attenuation also happens to radio waves and microwaves, as they are absorbed and scattered by specific molecules in the atmosphere. Attenuation can affect a network since it limits the length of network cabling over which you can send a message. If the cable is too long or too attenuating, 1 bit sent from the source can look like a 0 bit by the time it gets to the destination.

You can resolve this problem through the networking media that you choose, and by choosing structures that are designed to have low amounts of attenuation. One way to fix the problem is to change the medium. A second way is to use a repeater after a certain distance. There are repeaters for electrical, optical, and wireless bits.

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