Amateur radio
Amateur radio, also known as ham radio, is the use of the radio spectrum for non-commercial communication, technical experimentation, self-training, recreation, radiosport, contesting, and emergency communications. In 1927 a radio amateur was defined as "a duly authorized person interested in radioelectric practice with a purely personal aim and without pecuniary interest," meaning without monetary or similar reward. The definition distinguished amateur activity from commercial broadcasting, public safety services, and professional two-way radio uses such as maritime, aviation, and taxi communication.
The amateur radio service is established by the International Telecommunication Union through its Radio Regulations. National governments set technical and operational rules for transmissions and issue individual station licences with unique call signs. Call signs must be used in transmissions, at least every ten minutes and at the end. Amateur radio operators must hold an [|amateur radio licence], granted after an examination that tests knowledge of radio theory, electronics, and national regulations.
Operators are authorised to transmit on frequency ranges allocated internationally as the amateur radio bands. Within these bands they may use any frequency, though some are restricted to particular modes of voice, text, image, or data communications. This allows communication locally, nationally, worldwide, and even with stations in space. In many countries, operators may also exchange radio communications between computers or transceivers connected through virtual private networks on the Internet.
Amateur radio is represented by the International Amateur Radio Union, which has three regions and includes national amateur radio societies in most countries. In 2011 the American Radio Relay League estimated that about 2 million people worldwide were active in amateur radio. About 830,000 amateur radio stations are in Region 2, about 750,000 in Region 3, and about 400,000 in Region 1.
History
The origins of amateur radio can be traced to the late 19th century, but amateur radio as practised today began in the early 20th century. The First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations. This radio callbook lists wireless telegraph stations in Canada and the United States, including 89 amateur radio stations. As with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science, engineering, industry, and social services. Research by amateur operators has founded new industries, like experimentation with quartz piezoelectric resonators from 1924 until about 1934 built economies, empowered nations, and saved lives in times of emergency. Ham radio can also be used in the classroom to teach English, map skills, geography, math, science, and computer skills.Ham radio
The term "ham" was first a pejorative term used in professional wired telegraphy during the 19th century, to mock operators with poor Morse code-sending skills. This term continued to be used after the invention of radio, and the proliferation of amateur experimentation with wireless telegraphy; among land- and sea-based professional radio telegraphers, "ham" amateurs were considered a nuisance. The use of "ham" meaning "amateurish or unskilled" survives today sparsely in other disciplines.The amateur radio community subsequently reclaimed the word as a label of pride, and by the mid-20th century it had lost its pejorative meaning. Although not an acronym or initialism, it is occasionally written as "HAM" in capital letters.
Activity and practice
Amateur radio combines communication, technical experimentation, and recreation. Operators take part in contests, provide emergency service, build and modify equipment, and use transmission modes ranging from traditional Morse code to modern digital protocols.Community and social use
Operators often join conversational groups and take part in scheduled on-air meetings called nets, coordinated by a net control station. Nets may provide training for emergencies, operate as informal discussions, or focus on specialised topics.With battery- or generator-powered equipment, operators frequently provide communication during natural disasters when commercial services are unavailable.
Competitive activities include contests to contact as many stations as possible in a set period, and operating awards such as Summits on the Air, Worked All States, and Jamboree on the Air. Operators also contribute to citizen science by collecting propagation data and supporting atmospheric science research.
Voice and Morse code
The principal voice modes are frequency modulation, single sideband, and amplitude modulation. FM offers high audio quality, SSB is efficient for long-distance use, and AM continues among users of vintage amateur radio equipment.Radiotelegraphy using International Morse code, or continuous wave, is one of the oldest modes in amateur radio. Although largely replaced in professional services, it remains in use on shortwave bands because it functions under weak-signal conditions and employs internationally understood codes such as the Q code. CW is also used by hobbyists who build their own equipment and by operators engaged in low-power operation, as CW transmitters are simple to construct and weak signals can often be received by ear.
Until 2003, Morse code proficiency was required under international regulations for access to frequencies below 30 MHz. The requirement was withdrawn in the United States in 2007.
Digital and computer-assisted modes
Personal computers have enabled new digital transmission modes. Radioteletype, once operated by mechanical devices, is now handled in software. Packet radio, developed in the 1970s, uses protocols such as AX.25 and TCP/IP. Later modes including PSK31 and FT8 allow efficient low-signal communication on shortwave bands.Radio over IP applies Internet-based telephony techniques to radio. EchoLink and the Internet Radio Linking Project link repeaters and operators worldwide.
Other specialised modes support weak-signal communication. Automatic link establishment maintains networks on high frequency bands, while the WSJT suite supports meteor scatter and moonbounce.
Television and repeater systems
Fast-scan amateur television adapts consumer video equipment to transmit images. It typically operates on the 70 cm but may also use the 33 cm and higher frequencies. Because of wide bandwidth requirements, ATV usually covers 30–100 km. Linked repeater systems extend this range to several hundred kilometres. Repeaters are often located on high ground or towers and may be linked by other amateur bands, landlines, or the Internet.Space and atmospheric propagation
Operators can use amateur radio satellites, sometimes with only a hand-held transceiver. Natural reflectors such as the Moon, the aurora borealis, and meteor trails are also used. Licensed astronauts have also made contacts from the International Space Station through the ARISS programme.Licensing
Because radio signals can propagate across national borders, amateur radio is regulated by governments under international frameworks. National requirements generally follow standards set by the International Telecommunication Union and World Radiocommunication Conferences.Most countries require candidates to pass an examination that tests electronics, radio propagation, operating practices, and regulations. Licensing grants access to a broader portion of the spectrum, additional communication modes, and higher transmitter power than unlicensed personal radio services such as CB, FRS, or PMR446.
Examination systems often include several levels, each granting wider frequency access and higher power limits. In the United Kingdom and Australia, entry-level candidates must also complete a practical skills test to obtain the Foundation Licence, the first of three licensing stages.
Each licensee is normally assigned a unique call sign. Some countries issue additional station licences, or recognise club and organisational licences.
File:ICOM IC-P7 dscn2510a.jpg|thumb|right|A handheld VHF/UHF transceiver
Licences are generally valid only in the issuing country or in states with reciprocal agreements. In some jurisdictions, a licence is also required to purchase or possess amateur radio equipment.
In the United States, the Federal Communications Commission issues three licence classes: Technician, General, and Amateur Extra. Examinations are administered by accredited Volunteer Examiners through the FCC's Volunteer Examiner Coordinator system. Higher licence classes provide access to more frequency bands and higher transmitter power. The tests cover regulations, operating practices, electronics theory, equipment design, and safety. Morse code is no longer tested. Licences are valid for ten years, and the national question pools are published in advance and updated every four years.
Licensing requirements
Prospective amateur radio operators are examined on understanding of the key concepts of electronics, radio equipment, antennas, radio propagation, RF safety, and the radio regulations of the government granting the license. These examinations are sets of questions typically posed in either a short answer or multiple-choice format. Examinations can be administered by bureaucrats, non-paid certified examiners, or previously licensed amateur radio operators.The ease with which an individual can acquire an amateur radio license varies from country to country. In some countries, examinations may be offered only once or twice a year in the national capital and can be inordinately bureaucratic or challenging because some amateurs must undergo difficult security approval. Currently, only Yemen and North Korea do not issue amateur radio licenses to their citizens. Some developing countries, especially those in Africa, Asia, and Latin America, require the payment of annual license fees that can be prohibitively expensive for most of their citizens. A few small countries may not have a national licensing process and may instead require prospective amateur radio operators to take the licensing examinations of a foreign country. In countries with the largest numbers of amateur radio licensees, such as Japan, the United States, Thailand, Canada, and most of the countries in Europe, there are frequent license examinations opportunities in major cities.
Granting a separate license to a club or organization generally requires that an individual with a current and valid amateur radio license who is in good standing with the telecommunications authority assumes responsibility for any operations conducted under the club license or club call sign. A few countries may issue special licenses to novices or beginners that do not assign the individual a call sign but instead require the newly licensed individual to operate from stations licensed to a club or organization for a period of time before a higher class of license can be acquired.