In telecommunication, the term repeater has the following meanings:
- An analog device that amplifies an input signal regardless of its nature (analog or digital).
- A digital device that amplifies, reshapes, retimes, or performs a combination of any of these functions on a digital input signal for retransmission.
(Source: from Federal Standard 1037C in support of MIL-STD-188)
A repeater is an electronic device that receives a weaker signal and retransmits it at a higher level, so that the signal can cover longer distances without degradation. The term "repeater" originated with telegraphy and referred to an electromechanical device used to regenerate telegraph signals. Use of the term has continued in telephony and data communications.
A digipeater is a portmanteau meaning "digital repeater", particularly used in amateur radio.
Telecom cables
Repeaters are often used in trans-continental and trans-oceanic cables, because the attenuation (signal loss) over such distances would be completely unacceptable without them. Repeaters are not only used in copper-wire cables carrying electrical signals, but in fibre optics carrying light as well.
Duplex radio
In dispatching, amateur radio, and emergency services communications, repeaters are used extensively to relay radio signals across a wider area. With most emergency (and some other) dispatching systems, the repeater is synonymous with the base station, which performs both functions. This includes police, fire brigade, ambulance, taxicab, tow truck, and other services.
In amateur radio, repeaters are typically not used as a base station by a single user or group, however they do provide other services such as an autopatch connection to a POTS/PSTN phone line for remote users. These types of repeaters typically have a squelch tone (CTCSS or PL tone) implemented, to prevent them from being keyed-up (operated) accidentally by interference from other repeaters.
Broadcasting
Repeaters are also used extensively in broadcasting, where they are known as translators or boosters. See broadcast translator for more.