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.

In amateur radio, repeaters are typically maintained by individual hobbyists or local groups of amateur radio operators. 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 covers most of California at http://www.winsystem.org . Amateur radio station with modern solid-state transceiver featuring LCD and DSP capabilities Amateur radio, often called ham radio, is both a hobby and a service that uses various types of radio communications equipment to communicate with other radio amateurs for public service, recreation and self-training. ... A hobby is a spare-time recreational pursuit. ... Amateur Radio A remote base station is a common name for an Amateur Radio Auxiliary station that is set up as to be controlled and operated from a remote location. ...

Services provided by a repeater may include an autopatch connection to a POTS/PSTN telephone line to allow users to make telephone calls from their keypad-equipped radios. These advanced services may be limited to members of the group or club that maintains the repeater. Many amateur radio repeaters typically have a squelch tone (CTCSS or PL tone) implemented to prevent them from being keyed-up (operated) accidentally by interference from other radio signals. An autopatch is a feature of an amateur radio (or other type of two-way radio) repeater to access an outgoing telephone connection. ... Plain old telephone service, or POTS, are the services available from analogue telephones prior to the introduction of electronic telephone exchanges into the public switched telephone network. ... The public switched telephone network (PSTN) is the concatenation of the worlds public circuit-switched telephone networks, in much the same way that the Internet is the concatenation of the worlds public IP-based packet-switched networks. ... For other uses, see Telephone (disambiguation). ... In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver in the absence of a sufficiently strong desired input signal. ... In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver. ... In telecommunications, squelch is a circuit function that acts to suppress the audio (or video) output of a receiver. ... For other uses, see Interference (disambiguation). ...

In many communities, the repeater has become the on-the-air gathering spot for the local amateur radio community. Local public service nets may be heard on these systems and many are employed by weather spotters. In an emergency or a disaster a repeater can sometimes help to provide needed communications between areas that could not otherwise communicate. 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. In general, a spotter is someone trained to look for or spot something. ... Cellular redirects here. ...

Repeaters may also be linked together or connected to over the Internet using voice over IP (VoIP). Echolink allows hams with computers to connect to repeaters anywhere around the world and the Internet Radio Linking Project (IRLP) and App rpt/Asterisk allow for direct repeater linking. In addition, communications satellites called OSCARs have been launched with the specific purpose of operating as spaceborne amateur repeaters. IP Telephony, also called Internet telephony, is the technology that makes it possible to have a telephone conversation over the Internet or a dedicated Internet Protocol (IP) network instead of dedicated voice transmission lines. ... Echolink is a computer program that runs under Microsoft Windows to allow radio amateurs to communicate with one another using Voice over IP (VoIP) technology on the internet for at least part of the path between them. ... The Internet Radio Linking Project is a project within general amateur radio. ... App_rpt/Asterisk is a Radio Over IP (ROIP) application which runs on the Asterisk_PBX. App_rpt/Asterisk can be used to connect several repeaters and remote bases together using the Internet. ... U.S. military MILSTAR communications satellite A communications satellite (sometimes abbreviated to comsat) is an artificial satellite stationed in space for the purposes of telecommunications using radio at microwave frequencies. ... OSCAR is an acronym for Orbital Satellite Carrying Amateur Radio. ...

In the UK, repeaters are managed by the Emerging Technology Co-ordination Committee of the Radio Society of Great Britain ([2])and licenced by Ofcom the industry regulator for communications. This article lacks information on the importance of the subject matter. ... Ofcom is a regulator for communication industries in the United Kingdom. ...

Equipment

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. In telecommunications, frequency modulation (FM) conveys information over a carrier wave by varying its frequency. ...

Ham repeaters are found mainly in the VHF two meter (144 - 148 MHz) and the UHF 70 centimeter (420 - 450 MHz) bands, but can be used on almost any frequency pair above 29 MHz. Note that different countries have different rules; for example, in the United States, the two meter band is 144-148MHz, while in the United Kingdom and most of Europe) it's 144-146MHz. Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. ... 2 Meters is a popular amateur radio band. ... Ultra high frequency (UHF) designates a range (band) of electromagnetic waves whose frequency is between 300 MHz and 3. ... 70 Centimeters is a common ham radio band in the UHF spectrum. ... The 10 meter amateur radio band is the highest of the High Frequency or HF bands. ...

Repeater frequency sets are known as "repeater pairs," and in the ham radio community most follow ad hoc standards for the difference between the two frequencies. In the two-meter band, the standard is a 600 kHz shift, but some non-conforming oddball-split repeaters can be found in various places. The actual frequency pair used is assigned by a local frequency coordinating council.

In the days of crystal-controlled radios, these pairs were identified by the last portion of the transmit (Input) frequency followed by the last portion of the receive (Output) frequency that the ham would put into the radio. Thus "three-four nine-four" (34/94) meant that hams would transmit on 146.34MHz and listen on 146.94MHz (while the repeater would do the opposite, listening on 146.34 and transmitting on 146.94). In areas with many repeaters, "reverse splits" were common (i.e., 94/34), to prevent interference between systems.

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. In 1980, a ham might have been told that a repeater was on "22/82" -- today they will most often be told "682 down." The 6 refers to the last digit of 146MHz, so that the display will read "146.82" (the output frequency), and the radio is set to transmit "down" 600kHz on 146.22MHz.

Repeaters typically have a timer to cut off retransmission of a signal that goes too long. 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. The time restarts after a short pause following each transmission, and many feature a beep or chirp tone to signal that this has taken place.

A type of system known as a simplex repeater uses a single transceiver and a short-duration recorder, which records whatever the receiver picks up for a set length of time, then plays back the recording over the transmitter on the same frequency. A common name for them is a "parrot" repeater.

Another form of repeater is used in amateur packet radio, a form of digital computer-to-computer communications, and are dubbed "digipeaters" (for DIGItal rePEATERS).

Standard repeaters require either the use of two antennas (one each for transmitter and receiver) or a diplexer (also duplexer) to isolate the transmit and receive signals over a single antenna. The Duplexer is a device which prevents the repeater's high power transmitter (on the output frequency) from drowning out the users' signal on the repeater receiver (on the input frequency).

Most repeaters are remotely controlled through the use of audio tones on a control channel.

Repeaters can be setup as a "Link System" where transmitting on one repeater simultaneously transmits on all repeaters in the system. These systems are used for area or regional communications, for example in Skywarn. An example of a linked repeater system can be found here. SKYWARN is a program of the United States National Weather Service (NWS). ...

See also

Replexer A replexer is a device most commonly used in amateur radio to retransmit signals on one radio frequency band on to another. ...

External links

• http://www.repeater-builder.com - a free information web site devoted to those that build repeaters of any type: amateur, commercial, GMRS, public safety, etc.
• http://www.usrepeaters.com - list of over 23,000 repeaters in the United States and elsewhere
• http://k5ehx.net/repeaters/ - Display repeaters on map