Amateur radio operators enjoy personal two-way communications with friends, family members, and complete strangers, all of whom must also be licensed. They support the larger public community with emergency and disaster communications. Increasing a person's knowledge of electronics and radio theory as well as radio contesting are also popular aspects of amateur radio.
Radio amateurs use a variety of modes of transmission to communicate with one another. Voice transmissions are the most common way hams communicate with one another, with some types of emission such as frequency modulation (FM) offering high quality audio for local operation where signals are strong, and others such as single sideband (SSB) offering more reliable communications when signals are marginal and using smaller amounts of bandwidth.
Radiotelegraphy using Morse code remains surprisingly popular, particularly on the shortwave bands and for experimental work on the microwave bands, with its inherent signal-to-noise ratio advantages. Morse, using internationally agreed code groups, can also facilitate communications between amateurs who do not share a common language. Radiotelegraphy is also popular with home constructors as CW-only transmitters are simple to construct when compared to voice transmitters.
The explosion in personal computing power has led to a boom in digital modes such as radioteletype, which a generation ago required cumbersome and expensive specialist equipment. Hams led in the development of packet radio, which has since been augmented by more specialized modes such as PSK31 which is designed to facilitate real-time, low-power communications on the shortwave bands. Other modes, such as the WSJT suite, are aimed at extremely marginal propagation modes including meteor scatter and moonbounce or Earth-Moon-Earth (EME).
Similarly, fast scan amateur television, once considered rather esoteric, has exploded in popularity thanks to cheap camcorders and good quality video cards in home computers. Because of the wide bandwidth and stable signals required, fast scan amateur television is limited in range to at most 100 km (about 60 miles) in normal conditions.
The modes noted above are typically used in direct, radio-to-radio communication. On VHF and higher frequencies, automated relay stations, or repeaters, are used to increase range. Repeaters are usually located on the top of a mountain or tall building. A repeater allows the radio amateur to communicate over hundreds of square miles using only a relatively low power hand-held transceiver. Repeaters can also be linked together, either by use of other amateur radio bands, by wireline, or, increasingly via the Internet.
While many hams just enjoy talking to friends, others pursue interests such as providing communications for a community emergency response team; antenna theory; communication via amateur satellites ; disaster response; severe weather spotting; DX communication over thousands of miles using the ionosphere to refract radio waves; the Internet Radio Linking Project (IRLP) which is a composite network of radio and the Internet; Automatic Position Reporting System (APRS), which is a system of remote positioning that uses GPS; Contesting; the sport of Amateur Radio Direction Finding; High Speed Telegraphy; or low-power operation.Most hams have a room or area in their home which is dedicated to their radio and ancillary test equipment, known as the "shack" in ham slang.
Many hams enjoy meeting each other in person at events held in various locations. These annual events are generally known as a hamfest
Traditionally, radio amateurs exchange QSL cards with other stations to provide written confirmation of a conversation (QSO). These are required for many amateur operating awards, and many amateurs also enjoy collecting them simply for the pleasure of doing so.In contrast to most commercial and personal radio services, most radio amateurs are not restricted to using type-approved equipment, and therefore some radio amateurs home-construct or modify equipment in any way so long as they meet national and international standards on spurious emissions.
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 facilitate 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 permitted power levels are moderate by commercial standards, they are sufficient to enable cross-continental communication even with the least effective antenna systems and world-wide communications at least occasionally even with moderate antennas. Power limits vary from country to country. for For example, the highest license classes are: 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, 400 watts in the United Kingdom, 300 watts in Italy and 150 watts in Oman. Lower license classes are usually restricted to lower power limits; for example, the lowest license class in the UK has a limit of just 10 watts.
Some people suggest that the amateur portion of the radio spectrum is like a national park: something like the Yosemite of natural phenomenon. Through the licensing requirement, radio amateurs become like trained national park guides and backpackers. Where the backpackers and guides know about the beauty of the parks as well as the rules of engagement with wildlife in the park system, radio amateurs learn to appreciate and respect the beauty of the very limited electromagnetic space and the rules of engagement of human interaction within that space. In contrast, all of humanity benefits from the radio spectrum's existence, although it can not actually be seen.
In the United States, the Federal Communications Commission licenses operators in the Amateur Service as part of a mission that includes radio experimentation, public service, and the maintaining of a trained pool of technically-oriented operators. In exchange for learning the information needed to pass the federal test, licensed operators are allowed to use some 1300 distinct modes of communications at power levels ranging from microwatts to thousands of watts, effective radiated power
