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Radiogram (message)
A radiogram is a formal written message transmitted by radio. Also known as a radio telegram or radio telegraphic message, radiograms use a standardized message format, form and radiotelephone and/or radiotelegraph transmission procedures. These procedures typically provide a means of transmitting the content of the messages without including the names of the various headers and message sections, so as to minimize the time needed to transmit messages over limited and/or congested radio channels. Various formats have been used historically by maritime radio services, military organizations, and Amateur Radio organizations. Radiograms are typically employed for conducting Record communications, which provides a message transmission and delivery audit trail. Sometimes these records are kept for proprietary purposes internal to the organization sending them, but are also sometimes legally defined as public records. For example, maritime Mayday/SOS messages transmitted by radio are de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Record Communications
A record, recording or records may refer to: An item or collection of data Computing * Record (computer science), a data structure ** Record, or row (database), a set of fields in a database related to one entity ** Boot sector or boot record, record used to start an operating system ** Storage record, a basic input/output structure Documents * Record, a document ** Business record, of economic transactions ** Criminal record, a list of a person's criminal convictions ** Docket (court), the summary of proceedings in a court (US) ** Medical record, of a person's medical history and treatments ** Minutes, a summary of the proceedings at a meeting ** Public records, information that has been filed or recorded by public agencies ** Recording (real estate), the act of documenting real estate transactions ** Service record, usually associated with military service ** Transcript (law), a verbatim ''record'' of some proceedings, in particular a court transcript is a record of a law ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleprinter
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initially they were used in telegraphy, which developed in the late 1830s and 1840s as the first use of electrical engineering, though teleprinters were not used for telegraphy until 1887 at the earliest. The machines were adapted to provide a user interface to early mainframe computers and minicomputers, sending typed data to the computer and printing the response. Some models could also be used to create punched tape for data storage (either from typed input or from data received from a remote source) and to read back such tape for local printing or transmission. Teleprinters could use a variety of different communication media. These included a simple pair of wires; dedicated non-switched telephone circuits (leased lines); switched ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fldigi
Fldigi (short for Fast light digital) is a free and open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem. The software is mostly used by amateur radio operators who connect the microphone and headphone connections of an amateur radio SSB or FM transceiver to the computer's headphone and microphone connections, respectively. This interconnection creates a "sound card defined radio" whose available bandwidth is limited by the sound card's sample rate and the external radio's bandwidth. Such communications are normally done on the shortwave amateur radio bands in modes such as PSK31, MFSK, RTTY, Olivia, and CW (Morse code). Increasingly, the software is also being used for data on VHF and UHF frequencies using faster modes such as 8-PSK. Using this software, it is possible for amateur radio operators to communicate worldwide while using only a few watts of RF power. Fldigi software is also used for amateur radio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortwave Receiver
A shortwave radio receiver is a radio receiver that can receive one or more shortwave bands, between 1.6 and 30 MHz. A shortwave radio receiver often receives other broadcast bands, such as FM radio, Longwave and Mediumwave. Shortwave radio receivers are often used by dedicated hobbyists called shortwave listeners. History While home built shortwave receivers had been used by amateur radio operators and radio experimenters prior to World War I, the first time shortwave radio reception was available to the general public was through the use of shortwave frequency converters sold as accessories to broadcast-band radio sets during the mid 1920s. Such converters were generally found unsatisfactory in performance, and so dedicated shortwave receiving sets soon appeared on the market. National Radio Company introduced the SW-2 "Thrill box" shortwave regenerative receiver in 1927, and later offered improved models, such as the highly regarded SW-3. Other notable early shortwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amplitude Modulation
Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation. AM was the earliest modulation method used for transmitting audio in radio broadcasting. It was developed during the first quarter of the 20th century beginning with Roberto Landell de Moura and Reginald Fessenden's radiotelephone experiments in 1900. This original form of AM is sometimes called double-sideband amplitude modulation (DSBAM), because the standard method produces sidebands on either side of the carrier frequency. Single-sideband modulation uses bandpass filters to eliminate one of the sidebands ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shortwave Radio
Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 metres); above the medium frequency band (MF), to the bottom of the VHF band. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon. This is called skywave or "skip" propagation. Thus shortwave radio can be used for communication over very long distances, in contrast to radio waves of higher frequency, which travel in straight lines ( line-of-sight propagation) and are limited by the visual horizon, about 64 km (40 miles). Shortwave broadcasts of radio programs played an important role in the early days of rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metadata
Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive information about a resource. It is used for discovery and identification. It includes elements such as title, abstract, author, and keywords. * Structural metadata – metadata about containers of data and indicates how compound objects are put together, for example, how pages are ordered to form chapters. It describes the types, versions, relationships, and other characteristics of digital materials. * Administrative metadata – the information to help manage a resource, like resource type, permissions, and when and how it was created. * Reference metadata – the information about the contents and quality of statistical data. * Statistical metadata – also called process data, may describe processes that collect, process, or produce s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio Net
An amateur radio net, or simply ham net, is an " on-the-air" gathering of amateur radio operators. Most nets convene on a regular schedule and specific frequency, and are organized for a particular purpose, such as relaying messages, discussing a common topic of interest, in severe weather (for example, during a Skywarn activation), emergencies, or simply as a regular gathering of friends for conversation. Net operation Nets operate more or less formally depending on their purpose and organization. Groups of nets may organize and operate in collaboration for a common purpose, such as to pass along emergency messages in time of disaster. One such system of nets is the National Traffic System (NTS), organized and operated by members of the American Radio Relay League (ARRL) to handle routine and emergency messages on a nationwide and local basis. Formal operation A formal, or ''directed'' net has a single ''net control station '' (NCS) that manages its operation for a given se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amateur Radio
Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communications. The term "amateur" is used to specify "a duly authorised person interested in radioelectric practice with a purely personal aim and without pecuniary interest;" (either direct monetary or other similar reward) and to differentiate it from commercial broadcasting, public safety (such as police and fire), or professional two-way radio services (such as maritime, aviation, taxis, etc.). The amateur radio service (''amateur service'' and '' amateur-satellite service'') is established by the International Telecommunication Union (ITU) through the Radio Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual station licenses with a unique identifying call sign, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARRL Radiogram
An ARRL radiogram is an instance of formal written message traffic routed by a network of amateur radio operators through traffic nets, called the National Traffic System (NTS). It is a plaintext message, along with relevant metadata (headers), that is placed into a traffic net by an amateur radio operator. Each radiogram is relayed, possibly through one or more other amateur radio operators, to a radio operator who volunteers to deliver the radiogram content to its destination. Form overview Radiogram forms facilitate a standard protocol between amateur radio operators, allowing much faster relay of formal messages. They do this by always having the message headers in a certain order, allowing operators to read and understand the headers without explicit verbal labels. This is especially important in hectic and stressful environments such as during a disaster, when many parties call upon radio operators to quickly transfer messages in and out of the affected areas. A typica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Affiliate Radio System
The Military Auxiliary Radio System (MARS) is a United States Department of Defense sponsored program, established as a separately managed and operated program by the United States Army, and the United States Air Force. The United States Navy-Marine Corps program closed in 2015. The program is a civilian auxiliary consisting primarily of licensed amateur radio operators who are interested in assisting the military with communications on a regional and national level when access to traditional forms of communication may no longer be available. The MARS programs also include active duty, reserve, and National Guard units; and Navy, Marine Corps units. MARS has a long history of providing worldwide auxiliary emergency communications during times of need. The combined two-service MARS programs (Army, and Air Force), volunteer force of over 3,000 dedicated and skilled amateur radio operators provide the backbone of the MARS program. The main benefit of MARS membership is enjoying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
