Amateur radio repeater

An amateur radio repeater is an electronic device that receives a weak or low-level amateur radio signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation.

Amateur radio repeaters are similar in concept to those used by public safety entities (police, fire department, etc.

Many repeaters are provided openly to other amateur radio operators and typically not used as a remote base station by a single user or group.

In some areas multiple repeaters are linked together to form a wide-coverage network, such as the linked system provided by the Independent Repeater Association[1] which covers most of western Michigan, or the Western Intertie Network System ("WINsystem") that now covers a great deal of California, and is in 17 other states, including Hawaii, along with parts of four other countries, Australia, Canada, Great Britain and Japan.

Since the late 1970s, the use of synthesized, microprocessor-controlled radios, and widespread adoption of standard frequency splits have changed the way repeater pairs are described.

A few use a digital code system called DCS, DCG or DPL (a Motorola trademark).

In the evenings local public service nets may be heard on these systems and many repeaters are used by weather spotters.

Until cellular telephones became popular, it was common for community repeaters to have "drive time" monitoring stations so that mobile amateurs could call in traffic accidents via the repeater to the monitoring station who could relay it to the local police agencies via telephone.

Amateur Radio Repeater Coordinators or coordination groups are all volunteers and have no legal authority to assume jurisdictional or regional control in any area where the Federal Communications Commission regulates the Amateur Radio Service.

The purpose of coordinating a repeater or frequency is to reduce harmful interference to other fixed operations.

Coordinating a repeater or frequency with other fixed operations demonstrates good engineering and amateur practice.

[5] The most basic repeater consists of an FM receiver on one frequency and an FM transmitter on another frequency usually in the same radio band, connected together so that when the receiver picks up a signal, the transmitter is keyed and rebroadcasts whatever is heard.

Repeaters operated by groups with an emphasis on emergency communications often limit each transmission to 30 seconds, while others may allow three minutes or even longer.

Repeating signals across widely separated frequency bands allows for simple filters to be used to allow one antenna to be used for both transmit and receive at the same time.

These output frequencies happen to be the same as standard cable television channels 57 and 58, meaning that anyone with a cable-ready analog NTSC TV can tune them in without special equipment.

Frequently DVB-S modulation is used for digital ATV, due to narrow bandwidth needs and high loss tolerances.

Several satellites with amateur radio equipment on board have been designed and built by universities around the world.

For example, NASA and AMSAT coordinated the release of SuitSat which was an attempt to make a low cost experimental satellite from a discarded Russian spacesuit outfitted with amateur radio equipment.

The repeaters on board a satellite may be of any type; the key distinction is that they are in orbit around the Earth, rather than terrestrial in nature.

The three most common types of OSCARs are linear transponders, cross-band FM repeaters, and digipeaters (also referred to as pacsats).

Any signal with a bandwidth narrower than the transponder's pass-band will be repeated; however, for technical reasons, use of modes other than SSB and CW are discouraged.

These systems may not be legally classified as "repeaters", depending on the definition set by a country's regulator.

These systems are used for area or regional communications, for example in Skywarn nets, where storm spotters relay severe weather reports.

A properly adjusted voting system can switch many times a second and can actually "assemble" a multi-syllable word using a different satellite receiver for each syllable.

VoIP links are a convenient way to connecting distant repeaters that would otherwise be unreachable by VHF/UHF radio propagation.

Popular VoIP amateur radio network protocols include AllStarLink/HamVoIP, D-STAR, Echolink, IRLP, WIRES and eQSO.