Amateur radio

Slow-scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.

Citizens band radio (also known as CB radio) is, in many countries, a system of short-distance radio communications between individuals typically on a selection of 40 channels within the 27 MHz (11 m) band.

Automatic Packet Reporting System (APRS) is an amateur radio-based system for real time tactical digital communications of information of immediate value in the local area.

A crystal radio receiver, also called a crystal set or cat's whisker receiver, is a very simple radio receiver, popular in the early days of radio.

Software-defined radio (SDR) is a radio communication system where components that have been typically implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system.

Earth–Moon–Earth communication (EME), also known as moon bounce, is a radio communications technique that relies on the propagation of radio waves from an Earth-based transmitter directed via reflection from the surface of the Moon back to an Earth-based receiver.

Push-to-talk (PTT), also known as press-to-transmit, is a method of having conversations or talking on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode.

The International Radiotelephony Spelling Alphabet, commonly known as the ICAO phonetic alphabet, sometimes called the NATO alphabet or spelling alphabet and the ITU radiotelephonic or phonetic alphabet, is the most widely used radiotelephonic spelling alphabet.

D-STAR (Digital Smart Technologies for Amateur Radio) is a digital voice and data protocol specification for amateur radio.

A transceiver is a device comprising both a transmitter and a receiver that are combined and share common circuitry or a single housing.

In radio communications, a sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process.

DXing is the hobby of receiving and identifying distant radio or television signals, or making two way radio contact with distant stations in amateur radio, citizens' band radio or other two way radio communications.

AX.25 (Amateur X.25) is a data link layer protocol derived from the X.

A superheterodyne receiver (often shortened to superhet) is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency.

The Mongolian Amateur Radio Society (MARS) (in Mongolian, Монголын радио сонирхогчдын холбоо) is a national non-profit organization for amateur radio enthusiasts in Mongolia.

Radioteletype (RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link.

The Dutch Amateur Radio Emergency Service (DARES), which was founded on 12 May 2004, is a non-profit organization made out of licensed radio amateurs in the Netherlands.

The ARLC - Associação de Radioamadores da Linha de Cascais aka Cascais Amateur Radio Association was founded on 28 December 2011 to promote Ham Radio activity especially for youngsters, unite all amateurs, work with emergency authorities and to support Amateur radio and science investigation.

The Utah VHF Society Non-Profit Group was originally founded 1968 in Bountiful Utah as Utah VHF Society.

SatNOGS (Satellite Networked Open Ground Station) project is a free software and open source hardware platform aimed to create a satellite ground station network.

The Waverley Amateur Radio Society (WARS) is an amateur radio society based in Rose Bay, a suburb of Sydney, New South Wales, Australia which operates under the call sign VK2BV.

Olivia MFSK is an amateur radioteletype protocol designed to work in difficult (low signal-to-noise ratio plus multipath propagation) conditions on shortwave bands.

A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency; a sine wave.

The Hellschreiber or Feldhellschreiber (also Hell-Schreiber named after its inventor Rudolf Hell) is a facsimile-based teleprinter invented by Rudolf Hell.

Most countries' amateur radio licences allow licensed operators to install and use radio transmission equipment while at sea.