repeater

A repeater is a device that receives a signal, preserves its original quality, and retransmits it at a higher level to extend the transmission distance or coverage. Repeaters are used across electrical, optical, and radio transmission paths to overcome attenuation and distortion that occur as signals travel.

Common types include electrical (or digital) repeaters, optical repeaters, and radio repeaters. Electrical repeaters amplify and retime signals on copper cables, often used to extend telephone or data lines. Optical repeaters or regenerators restore optical signals in fiber optic links, sometimes combining amplification with signal regeneration to maintain integrity over long distances. Radio repeaters, typical in two-way or broadcast systems, receive on one frequency and retransmit on another, usually at higher power or from a fixed location to cover larger areas.

Operation generally involves amplification, timing, and, in some cases, shaping of the signal to counteract degradation. True regeneration aims to restore the signal to its original form rather than simply boosting amplitude, which helps reduce accumulated distortion. Repeaters do not, in themselves, interpret or modify the data beyond this regeneration step, distinguishing them from more complex network devices.

In networking, a repeater is considered a layer-1 device and does not partition collision domains; hubs perform a similar function in older Ethernet networks, while switches operate at higher layers to separate collisions and provide more efficient traffic handling. Limitations include the amplification of noise, added latency, and limited ability to handle modern digital signaling without regeneration.