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Collins 207B-1 Transmitter
The Collins 207B-1 was a radio transmitter manufactured in 1951 by Collins Radio Company. Specifications The 207B-1 was capable of 35 kilowatts of RF output in amplitude modulation mode, and 50 kilowatts in continuous wave mode. The transmitter was designed for land-based operation within the frequencies of 4 to 26 MHz and was contained within five sheet metal cabinets bolted together to form a single unit with a weight of 16,800 pounds. Intended primarily for high speed telegraphy and broadcasting, the 207B-1 was capable of high power AM transmission and telegraphic or frequency-shift keying at speeds greater than 400 words per minute. It could also be used to amplify the power output of a single-sideband modulation transmitter to a peak envelope power of 30 kilowatts.Unclassified publications of Lincoln Laboratory, 1951 Usage In April 1951 the United States Coast Guard Cutter USCGC ''Courier'' was equipped with two 207B-1 transmitters during its time as a ship-borne radio r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collins207B
Collins may refer to: People Surname Given name * Collins O. Bright (1917–?), Sierra Leonean diplomat * Collins Chabane (1960–2015), South African Minister of Public Service and Administration * Collins Cheboi (born 1987), Kenyan middle-distance runner * Collins Denny (1854–1943), American Bishop of the Methodist Episcopal Church, South * Collins Denny Jr. (1899–1964), American pro-segregationist lawyer. * Collins Hagler (born 1935), Canadian football player * Collins Injera (born 1986), Kenyan rugby player * Collins H. Johnston (1859–1936), American football player, medical doctor, surgeon, and civic leader * Collins John (born 1985), Liberia-born Dutch footballer * Collins Mbesuma (born 1984), Zambian footballer nicknamed ''The Hurricane'' or ''Ntofontofo'' * Collins Mensah (born 1961), Ghanaian sprinter * Collins Nweke (born 1965), Belgian politician of the Green Party * Collins Obuya (born 1981), Kenyan cricketer Companies * Collins Aerospace, avionics manufa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency-shift Keying
Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for communication systems such as telemetry, weather balloon radiosondes, caller ID, garage door openers, and low frequency radio transmission in the VLF and ELF bands. The simplest FSK is binary FSK (BFSK). BFSK uses a pair of discrete frequencies to transmit binary (0s and 1s) information. With this scheme, the 1 is called the mark frequency and the 0 is called the space frequency. Modulating and demodulating Reference implementations of FSK modems exist and are documented in detail. The demodulation of a binary FSK signal can be done using the Goertzel algorithm very efficiently, even on low-power microcontrollers. Variations Multiple frequency-shift keying Continuous-phase frequency-shift keying In principle FSK can be implemented by using completely independent free-running oscillat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron Curtain
The Iron Curtain was the political boundary dividing Europe into two separate areas from the end of World War II in 1945 until the end of the Cold War in 1991. The term symbolizes the efforts by the Soviet Union (USSR) to block itself and its satellite states from open contact with the West, its allies and neutral states. On the east side of the Iron Curtain were the countries that were connected to or influenced by the Soviet Union, while on the west side were the countries that were NATO members, or connected to or influenced by the United States; or nominally neutral. Separate international economic and military alliances were developed on each side of the Iron Curtain. It later became a term for the physical barrier of fences, walls, minefields, and watchtowers that divided the "east" and "west". The Berlin Wall was also part of this physical barrier. The nations to the east of the Iron Curtain were Poland, East Germany, Czechoslovakia, Hungary, Romania, Bulgaria, Albania, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voice Of America
Voice of America (VOA or VoA) is the state-owned news network and international radio broadcaster of the United States of America. It is the largest and oldest U.S.-funded international broadcaster. VOA produces digital, TV, and radio content in 48 languages which it distributes to affiliate stations around the globe. It is primarily viewed by a non-American audience. VOA was established in 1942, and the VOA charter (Public Laws 94-350 and 103–415) was signed into law in 1976 by President Gerald Ford. VOA is headquartered in Washington, D.C., and overseen by the U.S. Agency for Global Media (USAGM), an independent agency of the U.S. government. Funds are appropriated annually under the budget for embassies and consulates. In 2016, VOA broadcast an estimated 1,800 hours of radio and TV programming each week to approximately 236.6 million people worldwide with about 1,050 employees and a taxpayer-funded annual budget of . While Voice of America is seen by some foreign list ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
USCGC Courier (WAGR-410)
The USCGC ''Courier'' (WAGR/WTR-410) was a cutter in the United States Coast Guard converted from the ''M/V Coastal Messenger'' a Maritime Commission Type C1-M-AV1 vessel.USCG. Courier, 1952. USCG. 2010-06-04. URL:http://www.uscg.mil/history/webcutters/Courier1952.asp. Accessed: 2010-06-04. (Archived by WebCite at https://www.webcitation.org/5qEcrF5JF) M/V ''Coastal Messenger'' (1945–1952) Originally launched in 1945 by Froemming Brothers of Milwaukee, Wisconsin as the M/V ''Coastal Messenger'', the ship was to be originally named ''Doddridge'' but was changed prior to acceptance by the Maritime Administration. The ship was originally designed as an inter-island shuttle for military and naval cargoes. She was designed to receive cargo from much larger Victory and Liberty ships and then deliver it to U.S. forces on small outlying islands but was actually never used for that purpose due to the end of World War II. In the late-1940s, the M/V ''Coastal Messenger'' was operated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Coast Guard Cutter
United States Coast Guard Cutter is the term used by the U.S. Coast Guard for its commissioned vessels. They are or greater in length and have a permanently assigned crew with accommodations aboard. They carry the ship prefix USCGC. History of the USCG cutters The Revenue Marine and the Revenue Cutter Service, as it was known variously throughout the late 18th and the 19th centuries, referred to its ships as cutters. The term is English in origin and refers to a specific type of vessel, namely, "a small, decked ship with one mast and bowsprit, with a gaff mainsail on a boom, a square yard and topsail, and two jibs or a jib and a staysail." With general usage, that term came to define any vessel of the United Kingdom's HM Customs and Excise and the term was adopted by the U.S. Treasury Department at the creation of what would become the Revenue Marine. Since that time, no matter what the vessel type, the service has referred to its vessels with permanently assigned crew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peak Envelope Power
Peak envelope power (PEP) is the average power over a single RF cycle at the crest of the modulation. This is an FCC definition. PEP is normally considered the occasional or continuously repeating crest of the modulation envelope under normal operating conditions. The United States Federal Communications Commission uses PEP to set maximum power standards for radio transmitters. AM PEP Assuming linear, perfectly symmetrical, 100% modulation of a carrier, PEP output of an AM transmitter is four times its carrier PEP; in other words, a typical modern 100-watt amateur transceiver is usually rated for no more than, and often less than, 25 watts carrier output when operating in AM.R. Dean Straw, ed. ''ARRL Handbook For Radio Amateurs''. Newington, Connecticut: American Radio Relay League, 1999, p. 15.6 PEP vs. average power PEP is equal to steady carrier power, or radiotelegraph dot or dash average power, in a properly-formed CW transmission. PEP is also equal to average power in a st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single-sideband Modulation
In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude modulation, it uses transmitter power and bandwidth more efficiently. Amplitude modulation produces an output signal the bandwidth of which is twice the maximum frequency of the original baseband signal. Single-sideband modulation avoids this bandwidth increase, and the power wasted on a carrier, at the cost of increased device complexity and more difficult tuning at the receiver. Basic concept Radio transmitters work by mixing a radio frequency (RF) signal of a specific frequency, the carrier wave, with the audio signal to be broadcast. In AM transmitters this mixing usually takes place in the final RF amplifier (high level modulation). It is less common and much less efficient to do the mixing at low power and then amplify it in a linear ampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Broadcasting
Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a :wikt:one-to-many, one-to-many model. Broadcasting began with AM radio, which came into popular use around 1920 with the spread of vacuum tube radio transmitters and radio receiver, receivers. Before this, all forms of electronic communication (early radio, telephone, and telegraph) were wikt:one-to-one, one-to-one, with the message intended for a single recipient. The term ''broadcasting'' evolved from its use as the agricultural method of sowing seeds in a field by casting them broadly about. It was later adopted for describing the widespread distribution of information by printed materials or by telegraph. Examples applying it to "one-to-many" radio transmissions of an individual station to multiple listeners appeared as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves. Transmitters are necessary component parts of all electronic devices that communicate by radio, such as radio and television broadcasting stations, cell phones, walkie-talkies, wireless computer networks, Bluetooth enabled devices, garage door openers, two-way radios in aircraft, ships, spacecraft, radar sets and navigational beacons. The term ''transmitter'' is usually limited to equipment that generates radio waves for communication purposes; or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as microwave ovens or diathermy equipment, are not usually called transmitters, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telegraphy
Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined and such systems are thus not true telegraphs. The earliest true telegraph put into widespread use was the optical telegraph of Claude Chappe, invented in the late 18th century. The system was used extensively in France, and European nations occupied by France, during the Napoleonic era. The electric telegraph started to replace the optical telegraph in the mid-19th century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initially used mostly as an aid to railway signalling. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continuous Wave
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle accelerator having a continuous output, as opposed to a pulsed output. Continuous wave is also the name given to an early method of radio transmission, in which a sinusoidal carrier wave is switched on and off. Information is carried in the varying duration of the on and off periods of the signal, for example by Morse code in early radio. In early wireless telegraphy radio transmission, CW waves were also known as "undamped waves", to distinguish this method from damped wave signals produced by earlier ''spark gap'' type transmitters. Radio Transmissions before CW Very early radio transmitters used a spark gap to produce radio-frequency oscillations in the transmitting antenna. The signals produced by these spark-gap transmitters c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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