Foundation concept: Cables and connectors.

Definition: Data encoded as pulses of light conducted along flexible transparent wires as a replacement for data sent as electrical pulses along a flexible metal wire.

Overview

The most familiar means for transmitting signals or data is by sending electrical impulses along a flexible metal (nearly always copper) wire. This has many advantages: electrical signals are the native internal infrastructure of all computing devices, so very little signal conversion is required; wires can easily be insulated to prevent cross-over with other signals; electronic signals travel along wire at the speed of light, so speed is maximized. There is also one major disadvantage: when electric currents pass through metal wires they generate magnetic fields, and when metal wires pass through varying magnetic fields, they pick up induced electric currents. This means that, whenever two signal wires run close together, they will interfere with each other, and whenever a wire passes near to any electronic device, it will pick up interference from it. Heavy-duty electro-mechanical devices, such as large electric motors, can easily generate enough interference to swamp any real signal, and even enough to damage connected electronic equipment.

Common alternatives, such as transmitting signals by radio or microwave, suffer from similar problems. Radio and microwave signals can not be insulated and can not be channeled along a “wire,” so multiple signals have to use significantly different wavelengths in order to avoid complete interference; electrically generated interference is still a problem for radio, and microwave signals need a straight “line-of-sight” unobstructed path to follow; and there may be significant environmental dangers associated with some wireless signals (there is some controversy, but microwave radiation in the environment is a major concern for many).