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Packet radio is a digital radio communications method used to send packets of data. Packet radio uses packet switching to transmit datagrams. This is very similar to how packets of data are transferred between nodes on the Internet. Packet radio can be used to transmit data long distances.
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. Radioteletype evolved from earlier landline teleprinter operations that began in the mid-1800s. The US Navy Department successfully tested printing telegraphy between an airplane and ground radio station in 1922. Later that year, the Radio Corporation of America successfully tested printing telegraphy via their Chatham, Massachusetts, radio station to the R.M.S. Majestic. Commercial RTTY systems were in active service between San Francisco and Honolulu as early as April 1932 and between San Francisco and New York City by 1934. The US military used radioteletype in the 1930s and expanded this usage during World War II. From the 1980s, teleprinters were replaced by personal computers (PCs) running software to emulate teleprinters.
Automatic Link Establishment, commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications. ALE is a feature in an HF communications radio transceiver system that enables the radio station to make contact, or initiate a circuit, between itself and another HF radio station or network of stations. The purpose is to provide a reliable rapid method of calling and connecting during constantly changing HF ionospheric propagation, reception interference, and shared spectrum use of busy or congested HF channels.
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters. Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or "skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances and for mountainous terrains which prevent line-of-sight communications. The band is used by international shortwave broadcasting stations (3.95–25.82 MHz), aviation communication, government time stations, weather stations, amateur radio and citizens band services, among other uses.
Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and other low-power low-bandwidth needs, designed for small scale projects which need wireless connection. Hence, Zigbee is a low-power, low data rate, and close proximity wireless ad hoc network.
Power-line communication carries data on a conductor that is also used simultaneously for AC electric power transmission or electric power distribution to consumers.
The Joint Tactical Radio System (JTRS) aimed to replace existing radios in the American military with a single set of software-defined radios that could have new frequencies and modes (“waveforms”) added via upload, instead of requiring multiple radio types in ground vehicles, and using circuit board swaps in order to upgrade. JTRS has seen cost overruns and full program restructurings, along with cancellation of some parts of the program. JTRS is widely seen as one of the DoD's greatest acquisition failures, having spent $6B over 15 years without delivering a radio.
The Bell 202 modem was an early (1976) modem standard developed by the Bell System. It specifies audio frequency-shift keying (AFSK) to encode and transfer data at a rate of 1200 bits per second, half-duplex. It has separate sets of circuits for 1200 bps and 300 bps rates. These signalling protocols, also used in third-party modems, are referred to generically as Bell 202 modulation, and any device employing it as Bell-202-compatible.
The term utility station is used to describe fixed radio broadcasters disseminating signals that are not intended for reception by the general public. Utility stations, as the name suggests, do broadcast signals that have an immediate practical use, by means of analog or usually digital modes; most often utility transmissions are of a "point-to-point" nature, intended for a specific receiving station. Utility stations are most prevalent on shortwave frequencies, though they are not restricted to the shortwave frequencies.
Multiple frequency-shift keying (MFSK) is a variation of frequency-shift keying (FSK) that uses more than two frequencies. MFSK is a form of M-ary orthogonal modulation, where each symbol consists of one element from an alphabet of orthogonal waveforms. M, the size of the alphabet, is usually a power of two so that each symbol represents log2M bits.
CLOVER is the name of a series or class of modem modulation techniques (“waveforms”) specifically designed for use over high frequency (HF) radio systems.
PACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, military or government users such as the US Department of Homeland Security, and radio stations in isolated areas to send and receive digital information via radio.
Winlink, or formally, Winlink Global Radio Email, also known as the Winlink 2000 Network, is a worldwide radio messaging system that uses amateur-band radio frequencies and government frequencies to provide radio interconnection services that include email with attachments, position reporting, weather bulletins, emergency and relief communications, and message relay. The system is built and administered by volunteers and is financially supported by the Amateur Radio Safety Foundation.
Clansman is the name of a combat net radio system (CNR) used by the British Army from 1976 to 2010.
WSJT-X is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team. The digital signal processing techniques in WSJT-X make it substantially easier for amateur radio operators to employ esoteric propagation modes, such as high-speed meteor scatter and moonbounce.
The AN/PRC-150(C) Multiband Radio, also known as the Falcon II, is a manpack, tactical HF and VHF radio manufactured by Harris Corporation. It holds an NSA certification for Type 1 encryption.
An international distress frequency is a radio frequency that is designated for emergency communication by international agreement.
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems are excluded from the field.
The Defence High Frequency Communications Service or the DHFCS is a British military beyond line-of-sight communication system operated by the Ministry of Defence (MOD) and used predominately by the UK Armed Forces, as well as other authorised users. The system operates from six transmitting and receiving sites across the United Kingdom and is controlled from a network control centre located at Forest Moor in North Yorkshire and a backup site at Kinloss Barracks in Moray. Overseas sites are located in Ascension Island, Cyprus and Falkland Islands. In 2003 VT Merlin Communications were awarded the contract to operate the system for a period of fifteen years on behalf of the Ministry of Defence. The system is to be replaced by the Defence Strategic Radio Service (DSRS) also operated by Babcock
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