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Frequency-hopping Spread Spectrum
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver (radio), receiver. FHSS is used to avoid interference, to prevent eavesdropping, and to enable code-division multiple access (CDMA) communications. The frequency band is divided into smaller sub-bands. Signals rapidly change ("hop") their carrier frequencies among the center frequencies of these sub-bands in a determined order. Interference at a specific frequency will affect the signal only during a short interval. FHSS offers four main advantages over a fixed-frequency transmission: # FHSS signals are highly resistant to narrowband Interference (communication), interference because the signal hops to a different frequency band. # Signals are difficult to intercept if the frequency-hopping pattern is not known. # Jamming is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transmitter
In electronics and telecommunications, a radio transmitter or just transmitter (often abbreviated as XMTR or TX in technical documents) is an electronic device which produces radio waves with an antenna (radio), antenna with the purpose of signal transmission to a radio receiver. The transmitter itself generates a radio frequency alternating current, which is applied to the Antenna (radio), antenna. When excited by this alternating current, the antenna Electromagnetic radiation, radiates radio waves. Transmitters are necessary component parts of all electronic devices that communicate by radio communication, radio, such as radio broadcasting, radio (audio) and television broadcasting stations, cell phones, walkie-talkies, Wireless LAN, 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 fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Title 47 CFR Part 15
Code of Federal Regulations, 'Title 47, Part 15(47 CFR 15) is an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions. It is a part of Title 47 of the Code of Federal Regulations (CFR), and regulates everything from spurious emissions to unlicensed low-power broadcasting. Nearly every electronics device sold inside the United States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market. Subparts A - General Subpart A includes 21 sections from 15.1 to 15.38. states that any radiator (that which emits radio energy), whether or not intentional, must be licensed unless it meets 47 CFR 15 or is otherwise exempted by the FCC. the definitions are defined by the definition given. contains a general provision that devices may not cause interference and must accept any interference received. You are cautioned that any changes or modif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks in World War II, Tanks and Air warfare of World War II, aircraft played major roles, enabling the strategic bombing of cities and delivery of the Atomic bombings of Hiroshima and Nagasaki, first and only nuclear weapons ever used in war. World War II is the List of wars by death toll, deadliest conflict in history, causing World War II casualties, the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Allied-occupied Germany, Germany, Allied-occupied Austria, Austria, Occupation of Japan, Japan, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polish Zloty
Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Polish people, people from Poland or of Polish descent * Polish chicken * Polish brothers (Mark Polish and Michael Polish, born 1970), American twin screenwriters * Kevin Polish, an American Paralympian archer Polish may refer to: * Polishing, the process of creating a smooth and shiny surface by rubbing or chemical action ** French polishing, polishing wood to a high gloss finish * Nail polish * Shoe polish * Polish (screenwriting), improving a script in smaller ways than in a rewrite See also * * * Polishchuk (surname) * Polonaise (other) A polonaise ()) is a stately dance of Polish origin or a piece of music for this dance. Polonaise may also refer to: * Polonaises (Chopin), compositions by Frédéric Chopin ** Polonaise in A-flat major, Op. 53 (, ''Heroic Polonaise''; ) * Polon ... {{Disambiguation, surname Language and nationality disambiguation pages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polish General Staff
Polish General Staff, formally known as the General Staff of the Polish Armed Forces ( Polish: ''Sztab Generalny Wojska Polskiego'') is the highest professional body within the Polish Armed Forces. Organizationally, it is an integral part of the Ministry of National Defence and the Chief of the General Staff is the highest ranking military officer at the Ministry. It was created in 1918, and was renamed the Main Staff (''Sztab Główny'') in 1928 before being reverted back to General Staff (''Sztab Generalny'') in 1945 by the Soviet backed Communist Government. Currently General Wiesław Kukuła holds the position of Chief of the General Staff of the Polish Armed Forces (''Szef Sztabu Generalnego Wojska Polskiego''). History and structure On 25 October 1918, a decision was made to establish the directorate of the chief of staff of the Polish Army. On 22 December 1928 the General Staff was renamed to the Main Staff (''Sztab Główny''). In September 1939, during the Invasion of Pol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leonard Danilewicz
Leonard Stanisław Danilewicz was a Polish engineer and, for some ten years before the outbreak of World War II, one of the four directors of the AVA Radio Company in Warsaw, Poland. Cipher Bureau work AVA designed and built radio equipment for the Polish General Staff's Cipher Bureau, which was responsible for the radio communications of the General Staff's ''Oddział II'' (Section II, the General Staff's intelligence section). Beginning in 1933, after the Cipher Bureau's mathematician- cryptologist Marian Rejewski reconstructed the German military Enigma rotor cipher machine, AVA built Enigma "doubles" as well as all the electro-mechanical equipment subsequently designed at the Cipher Bureau to expedite routine breaking and reading of Enigma ciphers. AVA's other directors were Edward Fokczyński, Antoni Palluth, and Leonard Danilewicz's elder brother, Ludomir Danilewicz. The company took its name from the combined radio callsigns of the Danilewicz brothers (''TPAV'') an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polish People
Polish people, or Poles, are a West Slavic ethnic group and nation who share a common History of Poland, history, Culture of Poland, culture, the Polish language and are identified with the country of Poland in Central Europe. The preamble to the Constitution of the Republic of Poland defines the Polish nation as comprising all the citizenship, citizens of Poland, regardless of heritage or ethnicity. The majority of Poles adhere to Roman Catholicism. The population of self-declared Poles in Poland is estimated at 37,394,000 out of an overall population of 38,512,000 (based on the 2011 census), of whom 36,522,000 declared Polish alone. A wide-ranging Polish diaspora (the ''Polish diaspora, Polonia'') exists throughout Eurasia, the Americas, and Australasia. Today, the largest urban concentrations of Poles are within the Warsaw metropolitan area and the Katowice urban area. Ethnic Poles are considered to be the descendants of the ancient West Slavic Lechites and other tribes t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting took place mainly in European theatre of World War I, Europe and the Middle Eastern theatre of World War I, Middle East, as well as in parts of African theatre of World War I, Africa and the Asian and Pacific theatre of World War I, Asia-Pacific, and in Europe was characterised by trench warfare; the widespread use of Artillery of World War I, artillery, machine guns, and Chemical weapons in World War I, chemical weapons (gas); and the introductions of Tanks in World War I, tanks and Aviation in World War I, aircraft. World War I was one of the List of wars by death toll, deadliest conflicts in history, resulting in an estimated World War I casualties, 10 million military dead and more than 20 million wounded, plus some 10 million civilian de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EE Times
''EE Times'' (''Electronic Engineering Times'') is an electronics industry magazine published in the United States since 1972. EE Times is currently owned by AspenCore, a division of Arrow Electronics since August 2016. Ownership and status ''EE Times'' was launched in 1972 by Gerard G. Leeds of CMP Publications Inc. In 1999, the Leeds family sold CMP to United Business Media for $900 million. After 2000, ''EE Times'' moved more into web publishing. The shift in advertising from print to online began to accelerate in 2007, and the periodical shed staff to adjust to the downturn in revenue. In July 2013, the digital edition migrated to UBM TechWeb's DeusM community platform. On June 3, 2016, UBM announced that ''EE Times'', along with the rest of its electronics media portfolio ( EDN, Embedded.com, TechOnline, and Datasheets.com), was being sold to AspenCore Media, a company owned by Arrow Electronics, for $23.5 million. The acquisition was completed on August 1, 2016. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telefunken
Telefunken was a German radio and television producer, founded in Berlin in 1903 as a joint venture between Siemens & Halske and the ''AEG (German company), Allgemeine Elektrizitäts-Gesellschaft'' (AEG) ("General electricity company"). Prior to World War I, the company set up the first world-wide network of communications and was the first in the world to sell electronic televisions with cathode-ray tubes, in Germany in 1934. The brand had several incarnations: * ''Gesellschaft für drahtlose Telegraphie Gesellschaft mit beschränkter Haftung, m.b.H., System Telefunken'', founded in 1903 as a joint venture between AEG and Siemens & Halske * ''Telefunken, Gesellschaft für drahtlose Telegraphie m.b.H.'', in 1923; since 1941 as subsidiary of AEG alone * ''Telefunken Gesellschaft mit beschränkter Haftung, GmbH'', in 1955 * ''Telefunken Aktiengesellschaft (AG)'', in 1963 * ''Allgemeine Elektrizitäts-Gesellschaft AEG-Telefunken'', created in 1967 through a merger between Telefunken ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jonathan Zenneck
Jonathan Adolf Wilhelm Zenneck (; ; 15 April 1871 – 8 April 1959) was a German physicist and electrical engineer. Zenneck improved the cathode-ray tube by adding a second deflection structure at right angles to the first, which allowed two-dimensional viewing of a waveform. This two-dimensional display is fundamental to the oscilloscope. Early years Zenneck was born in Ruppertshofen, Württemberg. In 1885, Zenneck entered the Evangelical-Theological Seminary in Maulbronn. In 1887, while in a Blaubeuren seminary, Zenneck learned Latin, Greek, French, and Hebrew. In 1889, Zenneck enrolled in the University of Tübingen. At the Tübingen Seminary, he studied mathematics and natural sciences. In 1894, Zenneck took the state examination in mathematics and natural sciences and the examination for his doctor's degree. His dissertation, supervised by Theodor Eimer, was on grass snake embryos. In 1894, Zenneck conducted zoological research (Natural History Museum, London). Be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Scientist
''American Scientist'' (informally abbreviated ''AmSci'') is an American bimonthly science and technology magazine published since 1913 by Sigma Xi, The Scientific Research Honor Society. In the beginning of 2000s the headquarters was moved to Research Triangle Park, (Durham), North Carolina. Each issue includes feature articles written by scientists and engineers who review research in fields from molecular biology to computer engineering. Each issue also includes the work of cartoonist A cartoonist is a visual artist who specializes in both drawing and writing cartoons (individual images) or comics (sequential images). Cartoonists differ from comics writers or comics illustrators/artists in that they produce both the litera ...s, including those of Sidney Harris, Benita Epstein, and Mark Heath. Also included is the ''Scientists' Nightstand'' that reviews a vast range of science-related books and novels. ''American Scientist Online'' () was launched in May 2003. Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
