Amateur radio

An example of an amateur radio station with three transceivers, amplifiers, and a computer for logging and for digital modes. On the wall are examples of various awards, certificates, and a reception report card (QSL card) from a foreign amateur station.

Amateur radio, often called ham radio, is both a hobby and a service in which participants, called "hams", use various types of radio communications equipment to communicate with other radio amateurs for public services, recreation and self-training.^[1] Amateur radio operation is licensed by an appropriate government entity (for example, by the Federal Communications Commission in the United States^[2]) as coordinated through the International Telecommunication Union.^[3]

An estimated two million people throughout the world are regularly involved with amateur radio.^[4]

The term "amateur" does not imply a lack of skill or quality, but rather that amateur radio and its operators work outside of an official, governmental or commercial capacity.

History

Although its origins can be traced to at least the late 1800s, amateur radio, as practiced today, did not begin until the early 1900s. The first listing of amateur radio stations is contained in the First Annual Official Wireless Blue Book of the Wireless Association of America in 1909.^[5] This first radio callbook lists wireless telegraph stations in Canada and the United States, including eighty-nine amateur radio stations. 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,^[6] built economies,^[7] empowered nations,^[8] and saved lives in times of emergency.^[9]

Activities and practices

Amateur radio operators 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, often over long distance, when signals are marginal and bandwidth is restricted, at the sacrifice of audio quality.

Radiotelegraphy using Morse code (also known as "CW" from "continuous wave") is an activity dating to the earliest days of radio. It is the wireless extension of land line (wire based) telegraphy developed by Samuel Morse and was the predominant real time long-distance communication method of the 19th century. Though computer-based (digital) modes and methods have largely replaced CW for commercial and military applications, many amateur radio operators still enjoy using the CW mode, particularly on the shortwave bands and for experimental work such as earth-moon-earth communication, with its inherent signal-to-noise ratio advantages. Morse, using internationally agreed message encodings such as the Q code, enables communication between amateurs who speak different languages. It is also popular with homebrewers as CW-only transmitters are simpler to construct. A similar "legacy" mode popular with home constructors is amplitude modulation (AM), pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology.

For many years, demonstrating a proficiency in Morse code was a requirement to obtain amateur licenses for the high frequency bands (frequencies below 30 MHz), but following changes in international regulations in 2003, countries are no longer required to demand proficiency.^[10] As an example, the United States Federal Communications Commission phased out this requirement for all license classes on February 23, 2007.^[11][12]

Modern personal computers have encouraged the use of digital modes such as radioteletype (RTTY), which previously required cumbersome mechanical equipment.^[13] Hams led the development of packet radio in the 1970s, which has employed protocols such as TCP/IP since the 1980s. Specialized digital modes such as PSK31 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,^[14] while IRLP has allowed the linking of repeaters to provide greater coverage area. Automatic link establishment (ALE) has enabled continuous amateur radio networks to operate on the high frequency bands with global coverage. Other modes, such as FSK441 using software such as WSJT, are used for weak signal modes including meteor scatter and moonbounce communications.

Fast scan amateur television has gained popularity as hobbyists adapt inexpensive consumer video electronics like camcorders and video cards in PCs. Because of the wide bandwidth and stable signals required, amateur television is typically found in the 70 cm (420 MHz–450 MHz) frequency range, though there is also limited use on 33 cm (902 MHz–928 MHz), 23 cm (1240 MHz–1300 MHz) and higher. These requirements also effectively limit the signal range to between 20 and 60 miles (30 km–100 km), however, the use of linked repeater systems can allow transmissions across hundreds of miles.^[15]

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 hand-held transceiver (HT), even, at times, using the factory "rubber duck" antenna.^[16] Hams also use the moon, the aurora borealis, and the ionized trails of meteors as reflectors of radio waves.^[17] Hams are also often able to make contact with the International Space Station (ISS),^[18] as many astronauts and cosmonauts are licensed as amateur radio operators.^[19]

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".^[20] Nets can allow operators to learn procedures for emergencies, be an informal round table or be topical, covering specific interests shared by a group.

Licensing

An amateur radio antenna tower

A handheld VHF/UHF transceiver

In all countries that license citizens to use amateur radio, operators are required to pass a licensing exam displaying knowledge and understanding of key concepts.^[21] 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 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.

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 call signs. Some countries such as the United Kingdom 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. Three sequential levels of licensing exams (Technician Class, General Class and Amateur Extra Class) are currently offered, which allow operators who pass them access to larger portions of the Amateur Radio spectrum and more desirable call signs.

Newcomers

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. Established amateurs who help newcomers are often referred to as "Elmers" within the ham community.^[22][23] 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)

Call signs

Upon licensing, a radio amateur's national government issues a unique call sign to the radio amateur. The holder of a call sign uses it on the air to legally identify the operator or station during any and all radio communication.^[24] In certain jurisdictions, an operator may also select a "vanity" call sign although these must also conform to the issuing government's allocation and structure used for Amateur Radio call signs.^[25] Some jurisdictions, such as the U.S., require that a fee be paid to obtain such a vanity call sign; in others, such as the UK, a fee is not required and the vanity call sign may be selected when the license is applied for.

Call sign structure as prescribed by the ITU, consists of three parts which break down as follows, using the call sign ZS1NAT as an example:

1. ZS – Shows the country from which the call sign originates and may also indicate the license class. (This call sign is licensed in South Africa, and is CEPT Class 1).
2. 1 – Gives the subdivision of the country or territory indicated in the first part (this one refers to the Western Cape).
3. NAT – The final part is unique to the holder of the license, identifying that person specifically.

Many countries do not follow the ITU convention for the numeral. In the United Kingdom the calls G2xxx, G3xxx, and G6xxx may be issued to stations, these are Full License Holders. Additional licenses are granted in respect of Foundation Licensees M3xxx and M6xxx, Intermediate Licensees 2E1xxx and 2E0xxx and Full License Holders M0xxx and M1xxx. In the United States, the numeral indicates the geographical district the holder resided in when the license was issued. Prior to 1978, US hams were required to obtain a new call sign if they moved out of their geographic district.

Also, for smaller entities, a numeral may be part of the country identification. For example, VP2xxx is in the British West Indies (subdivided into VP2Exx Anguilla, VP2Mxx Montserrat, and VP2Vxx British Virgin Islands), VP5xxx is in the Turks and Caicos Islands, VP6xxx is on Pitcairn Island, VP8xxx is in the Falklands, and VP9xxx is in Bermuda.

Online callbooks or callsign databases can be browsed or searched to find out who holds a specific callsign.^[26] Non-exhaustive lists of famous people who hold or have held amateur radio callsigns have also been compiled and published.^[27]

Privileges

Unlike other RF spectrum users, radio amateurs may build or modify transmitting equipment for their own use within the amateur spectrum without the need to obtain government certification of the equipment.^[28][29] 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^[30] so long as they meet certain technical parameters including occupied bandwidth, power, and maintenance of spurious emission.

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 of day. 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 FSTV) transmissions and high-speed data networks.

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.

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 kW in Canada, was 2 kW in the former Yugoslavia, 1.5 kW in the United States, 1 kW in Belgium and Switzerland, 750 W in Germany, 500 W in Italy, 400 W in Australia, India and the United Kingdom, and 150 W in Oman. Lower license classes usually have lower power limits; for example, the lowest license class in the UK has a limit of 10 W. Amateur radio operators are encouraged both by regulations and tradition of respectful use of the spectrum to use as little power as possible to accomplish the communication.^[31]

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.

Many jurisdictions issue specialty vehicle registration plates to amateur radio operators who provide proof of an amateur radio license.^[32][33] The fees for application and renewal are usually less than the standard rate for specialty plates.^[32][34]

Band plans and frequency allocations

The International Telecommunication Union (ITU) governs the allocation of communications frequencies worldwide, 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 148.800 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 providing essential communication needs in connection with the immediate safety of human life and immediate protection of property when normal communication systems are not available may use any frequency including those of other radio services such as police and fire communications and the Alaska statewide emergency frequency of 5167.5 kHz.

Similarly, amateurs in the United States may apply to be registered with the Military Auxiliary 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.

See also

• List of amateur radio magazines
• List of amateur radio modes
• List of amateur radio organizations
• Maritime mobile amateur radio

References

Further reading

• Bergquist, Carl J (May 2001). Ham Radio Operator's Guide (2nd ed.). Indianapolis: Prompt Publications. ISBN 0-7906-1238-0. 
• Dennison, Mike; Fielding, John, eds (2009). Radio Communication Handbook (10th ed.). Bedford, England: Radio Society of Great Britain. ISBN 9781-9050-8654-2. 
• Haring, Kristen (2007). Ham Radio's Technical Culture. Cambridge, MA: MIT Press. ISBN 0262083558. 
• Poole, Ian D (October 2001). HF Amateur Radio. Potters Bar, Hertfordshire, England: Radio Society of Great Britain. ISBN 1-872309-75-5. 
• Rohde, Ulrich L; Whitaker, Jerry C (2001). Communications Receivers: DSP, Software Radios, and Design (3rd ed.). New York City: McGraw-Hill. ISBN 0-07-136121-9. 
• The ARRL Handbook for Radio Communications 2010 (87th ed.). Newington, CT: American Radio Relay League. November 2009. ISBN 0-87259-144-1. 

External links

• Amateur Radio at the Open Directory Project