Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term wireless telegraphy was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code.
A communications system or communication system is a collection of individual telecommunications networks systems, relay stations, tributary stations, and terminal equipment usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union.
In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of transmitter and responder.
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television, telephone, radio, internet, and military applications. Many communications satellites are in geostationary orbit 22,300 miles (35,900 km) above the equator, so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit, where antennas on the ground have to follow the position of the satellites and switch between satellites frequently.
Wireless communication is the transfer of information (telecommunication) between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mouse, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications involve other electromagnetic phenomena, such as light and magnetic or electric fields, or the use of sound.
A radiotelephone, abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to radiotelegraphy, which is radio transmission of telegrams (messages), or television, transmission of moving pictures and sound. The term is related to radio broadcasting, which transmit audio one way to listeners. Radiotelephony refers specifically to two-way radio systems for bidirectional person-to-person voice communication between separated users, such as CB radio or marine radio. In spite of the name, radiotelephony systems are not necessarily connected to or have anything to do with the telephone network, and in some radio services, including GMRS, interconnection is prohibited.
The aircraft emergency frequency is a frequency used on the aircraft band reserved for emergency communications for aircraft in distress. The frequencies are 121.5 MHz for civilian, also known as International Air Distress (IAD) or VHF Guard, and 243.0 MHz—the second harmonic of VHF guard—for military use, also known as Military Air Distress (MAD) or UHF Guard. Earlier emergency locator transmitters (ELTs) used the guard frequencies to transmit, but an additional frequency of 406 MHz is used by a more modern emergency locator transmitter.
A flight service station (FSS) is an air traffic facility that provides information and services to aircraft pilots before, during, and after flights, but unlike air traffic control (ATC), is not responsible for giving instructions or clearances or providing separation. They do, however, relay clearances from ATC for departure or approaches. The people who communicate with pilots from an FSS are referred to as flight service specialists.
A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow for simultaneous communication in both directions between two connected parties or to provide a reverse path for the monitoring and remote adjustment of equipment in the field. There are two types of duplex communication systems: full-duplex (FDX) and half-duplex (HDX).
A UNICOM station is an air-ground communication facility operated by a non-air traffic control private agency to provide advisory service at uncontrolled aerodromes and airports and to provide various non-flight services, such as requesting a taxi, even at towered airports. It is also known as an aeronautical advisory station. The equivalent European/ICAO service is known as (aerodrome) flight information service, abbreviated as AFIS or FIS.
Flight Information Centres (FICs) are centres employing flight service specialists responsible for the management and dissemination of flight safety related information operated by Nav Canada.
In air traffic control, an area control center (ACC), also known as a center or en-route center, is a facility responsible for controlling aircraft flying in the airspace of a given flight information region (FIR) at high altitudes between airport approaches and departures. In the US, such a center is referred to as an air route traffic control center (ARTCC).
In aviation, a non-towered airport is an airport without a control tower, or air traffic control (ATC) unit. The vast majority of the world's airports are non-towered. In the United States, there are close to 20,000 non-towered airports compared to approximately 500 airports with control towers. Airports with a control tower without 24/7 ATC service follow non-towered airport procedures when the tower is closed but the airport remains open, for example at night.
Telecommunications engineering is a subfield of electronics engineering which seeks to design and devise systems of communication at a distance. The work ranges from basic circuit design to strategic mass developments. A telecommunication engineer is responsible for designing and overseeing the installation of telecommunications equipment and facilities, such as complex electronic switching systems, and other plain old telephone service facilities, optical fiber cabling, IP networks, and microwave transmission systems. Telecommunications engineering also overlaps with broadcast engineering.
The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components shared jointly with the military. It is one of the most complex aviation systems in the world, and services air travel in the United States and over large portions of the world's oceans.
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 3,000 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications.
During World War II, the German Luftwaffe relied on an increasingly diverse array of electronic communications, IFF and RDF equipment as avionics in its aircraft and also on the ground. Most of this equipment received the generic prefix FuG for Funkgerät, meaning "radio equipment". Most of the aircraft-mounted Radar equipment also used the FuG prefix. This article is a list and a description of the radio, IFF and RDF equipment.
Ground communications outlets (GCO) have been installed at some U.S. airports to provide a means for pilots on the ground to communicate with flight service stations and air traffic control (ATC) facilities for the purpose of filing, opening and closing VFR or IFR flight plans; obtaining weather briefings and clearances; and similar communications. Larger facilities instead have a remote communications outlet (RCO) installed, which allows pilots to communicate directly over a remote radio transmitter/receiver with the facility. A GCO instead connects with the aircraft/pilot via a radio transmitter/receiver, but with the ground facility via a telephone connection.
The low-frequency radio range, also known as the four-course radio range, LF/MF four-course radio range, A-N radio range, Adcock radio range, or commonly "the range", was the main navigation system used by aircraft for instrument flying in the 1930s and 1940s, until the advent of the VHF omnidirectional range (VOR), beginning in the late 1940s. It was used for en route navigation as well as instrument approaches and holds.
Air-to-ground communication was first made possible by the development of two-way aerial telegraphy in 1912, soon followed by two-way radio. By the Second World War, radio had become the chief medium of air-to-ground and air-to-air communication. Since then, transponders have enabled pilots and controllers to identify planes automatically, greatly improving air security. Most recently, in addition to sophisticated radio and GPS systems, the unmanned aerial vehicle, or drone, has revolutionised aerial surveillance and combat.
