From Wikipedia, the free encyclopedia

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 participant is called an amateur radio operator, or a ham.^[1]

Amateur radio operators enjoy personal wireless communications with each other and are able to support their communities with emergency and disaster communications if necessary, while increasing their personal knowledge of electronics and radio theory. An estimated six million people throughout the world are regularly involved with amateur radio.^[2]

The term "amateur" is not a reflection on the skills of the participants, which are often quite advanced; rather, "amateur" indicates that amateur radio communications are not allowed to be made for commercial or money-making purposes.

Main article: Amateur radio history

Though its origins can be traced to at least the late 1800s, amateur radio, as practiced today, began in the 1920s. As with radio in general, the birth of amateur radio was strongly associated with various amateur experimenters and hobbyists. Throughout its history, amateur radio enthusiasts have made significant contributions to science, engineering, industry, and social services. Research by amateur radio operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency.

The international symbol for amateur radio, included in the logos of many IARU member societies. The diamond holds a circuit diagram featuring components common to every radio: an antenna, inductor and ground.

Radio amateurs use various modes of transmission to communicate. Voice transmissions are most common, with some such as frequency modulation (FM) offering high quality audio, and others such as single sideband (SSB) offering more reliable communications when signals are marginal and bandwidth is restricted.

Radiotelegraphy using Morse code remains popular, particularly on the shortwave bands and for experimental work such as Moonbounce, with its inherent signal-to-noise ratio advantages. Morse, using internationally agreed code groups, also allows communications between amateurs who speak different languages. It is also popular with homebrewers as CW-only transmitters are simpler to construct. For many years, demonstrating a proficiency in Morse code was a requirement to obtain amateur licenses for the high frequency bands, but following changes in international regulations in 2003, many countries have now dropped this requirement (the United States Federal Communications Commission did so in February 2007).^[3]

Amateur radio operator, DJ1YFK running high-speed computer-generated telegraphy during a competition

Amateur radio operator MM3OXB operating HF on an FT857D

Amateur radio operator KB3HTS operating SSB

Modern personal computers have led to a boom in digital modes such as radioteletype, which previously required cumbersome mechanical equipment.^[4] Hams led the development of packet radio, which has even used protocols such as TCP/IP since the 1970s. This has since been augmented by more specialized modes such as PSK31 to allow real-time, low-power communications on the shortwave bands. Echolink using Voice over IP technology has enabled amateurs to communicate through local internet-connected repeaters and radio nodes, while IRLP has allowed easy linking together of repeaters. Other modes, such as FSK441 using software such as WSJT, are used for weak signal modes including meteor scatter and moonbounce communications.

Similarly, fast scan amateur television, once considered esoteric, has exploded in popularity thanks to cheap camcorders and video cards in home computers. Because of the wide bandwidth and stable signals required, amateur television is typically found in the 70 cm (420—450 MHz) frequency range, though there is also limited use on 33 cm (902—928 MHz), 23 cm (1240—1300 MHz) and higher. These requirements also effectively limit the signal range to between 20 and 60 miles (30—100 km), however, the use of linked repeater systems can allow transmissions across hundreds of miles.^[5]

These repeaters, or automated relay stations, are used on VHF and higher frequencies to increase signal range. Repeaters are usually located on top of a mountain, hill or tall building, and allow operators to communicate over hundreds of square miles using a low power hand-held transceiver. Repeaters can also be linked together by use of other amateur radio bands, landline or the Internet.

Communication satellites called OSCARs (Orbiting Satellite Carrying Amateur Radio) can be accessed, some using a handheld transceiver (HT) with a stock "rubber duck" antenna. Hams also use the moon and the ionized trails of meteors as reflectors of radio waves.^[6] Hams are also often able to make contact with the International Space Station (ISS),^[7] as many astronauts and cosmonauts are licensed as Amateur Radio Operators.^[8]

Amateur radio operators use their amateur radio station to make contacts with individual hams as well as participating in round table discussion groups or "rag chew sessions" on the air. Some join in regularly scheduled on-air meetings with other amateur radio operators, called "Nets" (as in "networks") which are moderated by a station referred to as "Net Control".^[9] Nets can allow operators to learn procedures for emergencies, be an informal round table or be topical, covering specific interests shared by a group.

Main article: Amateur radio license

In all countries, amateur radio operators are required to pass a licensing exam displaying knowledge and understanding of key concepts. In response, hams are granted operating privileges in larger segments of the radio frequency spectrum using a wide variety of communication techniques with higher power levels permitted. This practice is in contrast to other unlicensed personal radio services such as CB radio, Multi-Use Radio Service, or Family Radio Service / PMR446 that require type-approved equipment restricted in frequency range and power.

A handheld VHF/UHF transceiver, 2007.

In many countries, amateur licensing is a routine civil administrative matter. Amateurs are required to pass an examination to demonstrate technical knowledge, operating competence and awareness of legal and regulatory requirements in order to avoid interference with other amateurs and other radio services. There are often a series of exams available, each progressively more challenging and granting more privileges in terms of frequency availability, power output, permitted experimentation, and in some countries, distinctive callsigns. Some countries such as Great Britain and Australia have begun requiring a practical training course in addition to the written exams in order to obtain a beginner's license, called a Foundation License.

Amateur radio licensing in the United States serves as an example of the way some countries award different levels of amateur radio licenses based on technical knowledge. Licensees previously needed to demonstrate proficiency in Morse Code to obtain or upgrade a license. These requirements were phased out by the Federal Communications Commission, first from the entry-level Technician license in 1991, and eventually from all license classes on February 23, 2007.^[10] This conforms with international law, which no longer mandates Morse code testing, as well as views by the FCC that Morse code should be treated like other communications techniques, and that written testing is sufficient to prove that an applicant is qualified to obtain an amateur radio license.^[11] Some portions of the ham bands remain reserved for Morse code use only and the mode remains popular.

Many people start their involvement in amateur radio by finding a local club. Clubs often provide information about licensing, local operating practices and technical advice. Newcomers also often study independently by purchasing books or other materials, sometimes with the help of a mentor, teacher or friend. In addition, many countries have national amateur radio societies which encourage newcomers and work with government communications regulation authorities for the benefit of all radio amateurs. The oldest of these societies is the Wireless Institute of Australia, formed in 1910; other notable societies are the Radio Society of Great Britain, the American Radio Relay League, Radio Amateurs of Canada, the New Zealand Association of Radio Transmitters and South African Radio League. (See Category:Amateur radio organizations)

Upon licensing, a radio amateur's national government issues a unique callsign to the radio amateur. The holder of a callsign uses it on the air to legally identify the operator or station during any and all radio communication.^[12] In certain jurisdictions, an operator may also select a "vanity" callsign.^[13] Some jurisdictions, such as the U.S., require that a fee be paid to obtain such a vanity callsign; in others, such as the UK, a fee is not required and the vanity callsign may be selected when the license is applied for.

Unlike all other spectrum users, radio amateurs are allowed to build or modify transmitting equipment, and do not need to obtain type-approval for it. Licensed amateurs can also use any frequency in their bands (rather than being allocated fixed frequencies or channels) and can operate medium to high-powered equipment on a wide range of frequencies^[14] so long as they meet spurious emission standards.

As noted, radio amateurs have access to frequency allocations throughout the RF spectrum, enabling choice of frequency to enable effective communication whether across a city, a region, a country, a continent or the whole world regardless of season or time day or night. The shortwave bands, or HF, can allow worldwide communication, the VHF and UHF bands offer excellent regional communication, and the broad microwave bands have enough space, or bandwidth, for television (known as SSTV and FSTV) transmissions and high-speed data networks.

Although allowable power levels are moderate by commercial standards, they are sufficient to enable global communication. Power limits vary from country to country and between license classes within a country. For example, the power limits for the highest available license classes in a few selected countries are: 2.25 kilowatts in Canada, 2 kilowatts in most countries of the former Yugoslavia, 1.5 kilowatts in the United States, 1 kilowatt in Belgium and Switzerland, 750 watts in Germany, 500 watts in Italy, 400 watts in Australia and the United Kingdom, 150 watts in Oman and 100 watts in India. Lower license classes usually have lower power limits; for example, the lowest license class in the UK has a limit of just 10 watts.

When traveling abroad, visiting amateur operators must follow the rules of the country in which they wish to operate. Some countries have reciprocal international operating agreements allowing hams from other countries to operate within their borders with just their home country license. Other host countries require that the visiting ham apply for a formal permit, or even a new host country-issued license, in advance.

Main article: Amateur radio frequency allocations

The International Telecommunication Union (ITU) governs the allocation of communications frequencies world-wide, with participation by each nation's communications regulation authority. National communications regulators have some liberty to restrict access to these frequencies or to award additional allocations as long as radio services in other countries do not suffer interference. In some countries, specific emission types are restricted to certain parts of the radio spectrum, and in most other countries, International Amateur Radio Union (IARU) member societies adopt voluntary plans to ensure the most effective use of spectrum.

In a few cases, a national telecommunication agency may also allow hams to use frequencies outside of the internationally allocated amateur radio bands. In Trinidad and Tobago, hams are allowed to use a repeater which is located on 148.80 MHz. This repeater is used and maintained by the National Emergency Management Agency (NEMA), but may be used by radio amateurs in times of emergency or during normal times to test their capability and conduct emergency drills. This repeater can also be used by non-ham NEMA staff and REACT members. In Australia and New Zealand ham operators are authorized to use one of the UHF TV channels. In the U.S., in cases of emergency, amateur radio operators may use any frequency including those of other radio services such as police and fire communications and the Alaska statewide emergency frequency of 5165.7 kHz.

Similarly, amateurs in the United States may apply to be registered with the Military Affiliate Radio System (MARS). Once approved and trained, these amateurs also operate on US Government Military frequencies to provide contingency communications and morale message traffic support to the military services.

Amateur radio can be found throughout popular culture as a plot device. A classic example is the "Radio Ham" episode of 1960s British comedy series Hancock's Half Hour.

Amateur radio has also been featured in several movies. Jurassic Park featured the use of a "CQ call" (which is used to initiate a conversation with a listening station). The movie Frequency featured amateur radio as a core part of the plot, though it mocked the hobby, claiming that it was antiquated and no longer practiced.

There are many famous Amateur radio operators, such as King Juan Carlos I of Spain, the late Prime Minister of India Rajiv Gandhi and his wife Sonia Gandhi, Bollywood actor Amitabh Bachchan, US radio and TV host Walter Cronkite, and Coast To Coast AM host Art Bell. Others include US Gen. Curtis LeMay, Joe Walsh, Lance Bass, Barry Goldwater, Chet Atkins, Marlon Brando, King Hussein of Jordan, Patty Loveless, Ronnie Milsap, Bill "Bubba" Bussey from the nationally syndicated Rick and Bubba Show, Maine Governor John Baldacci, and Jean Shepherd, as well as most of the launched astronauts and cosmonauts. George Sweigert, inventor of the cordless phone, was an amateur radio operator as well. Edward S. Rogers, Sr., founder of Rogers Communications, was a licenced Amateur.

Wikimedia Commons has media related to:

Amateur radio

Cited References

General References

Electronics Portal

Radio Portal

• List of amateur radio magazines
• List of amateur radio operating modes
• List of amateur radio organizations

• Amateur Radio at the Open Directory Project