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Ionospheric
The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on Earth. History of discovery As early as 1839, the German mathematician and physicist Carl Friedrich Gauss postulated that an electrically conducting region of the atmosphere could account for observed variations of Earth's magnetic field. Sixty years later, Guglielmo Marconi received the first trans-Atlantic radio signal on December 12, 1901, in St. John's, Newfoundland (now in Canada) using a kite-supported antenna for reception. The transmitting station in Poldhu, Cornwall, used a spark-gap transmitter to produce a signal with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Propagation
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affected by the phenomena of reflection, refraction, diffraction, absorption, polarization, and scattering. Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for amateur radio communications, international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation, to operation of radar systems. Several different types of propagation are used in practical radio transmission systems. '' Line-of-sight propagation'' means radio waves which travel in a straight line from the transmitting antenna to the receiving antenna. Line of sight transmission is used for medium-distance radio transmission, such as cell phones, cordless phones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kennelly–Heaviside Layer
The Heaviside layer, sometimes called the Kennelly–Heaviside layer, named after Arthur E. Kennelly and Oliver Heaviside, is a layer of ionised gas occurring roughly between 90km and 150 km (56 and 93 mi) above the ground — one of several layers in the Earth's ionosphere. It is also known as the E region. It reflects medium-frequency radio waves. Because of this reflective layer, radio waves radiated into the sky can return to Earth beyond the horizon. This "skywave" or "skip" propagation technique has been used since the 1920s for radio communication at long distances, up to transcontinental distances. Propagation is affected by the time of day. During the daytime the solar wind presses this layer closer to the Earth, thereby limiting how far it can reflect radio waves. Conversely, on the night (lee) side of the Earth, the solar wind drags the ionosphere further away, thereby greatly increasing the range which radio waves can travel by reflection. The ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spark-gap Transmitter
A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark."Radio Transmitters, Early" in Spark-gap transmitters were the first type of radio transmitter, and were the main type used during the wireless telegraphy or "spark" era, the first three decades of radio, from 1887 to the end of World War I. German physicist Heinrich Hertz built the first experimental spark-gap transmitters in 1887, with which he proved the existence of radio waves and studied their properties. A fundamental limitation of spark-gap transmitters is that they generate a series of brief transient pulses of radio waves called damped waves; they are unable to produce the continuous waves used to carry audio (sound) in modern AM or FM radio transmission. So spark-gap transmitters could not transmit audio, and instead transmitted information by radiotelegraphy; the operator switched the transmitter on and off with a telegraph key, creating puls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge
Cambridge ( ) is a College town, university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge became an important trading centre during the Roman and Viking ages, and there is archaeological evidence of settlement in the area as early as the Bronze Age. The first Town charter#Municipal charters, town charters were granted in the 12th century, although modern city status was not officially conferred until 1951. The city is most famous as the home of the University of Cambridge, which was founded in 1209 and consistently ranks among the best universities in the world. The buildings of the university include King's College Chapel, Cambridge, King's College Chapel, Cavendish Laboratory, and the Cambridge University Library, one of the largest legal deposit libraries in the world. The city's skyline is dominated by several Colleg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guglielmo Marconi
Guglielmo Giovanni Maria Marconi, 1st Marquis of Marconi (; 25 April 187420 July 1937) was an Italian inventor and electrical engineer, known for his creation of a practical radio wave-based wireless telegraph system. This led to Marconi being credited as the inventor of radio, and he shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy".Guglielmo Marconi: The Nobel Prize in Physics 1909 . nobelprize.org Marconi was also an entrepreneur, businessman, and founder of The Wireless Telegraph & Signal Company in the |
Amateur Radio Operators
An amateur radio operator is someone who uses equipment at an amateur radio station to engage in two-way personal communications with other amateur operators on radio frequencies assigned to the amateur radio service. Amateur radio operators have been granted an amateur radio license by a governmental regulatory authority after passing an examination on applicable regulations, electronics, radio theory, and radio operation. As a component of their license, amateur radio operators are assigned a call sign that they use to identify themselves during communication. About three million amateur radio operators are currently active worldwide. Amateur radio operators are also known as radio amateurs or hams. The term "ham" as a nickname for amateur radio operators originated in a pejorative usage (like "ham actor") by operators in commercial and professional radio communities, and dates to wired telegraphy. The word was subsequently adopted by amateur radio operators. Demographics {, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Act Of 1912
The Radio Act of 1912, formally known as "An Act to Regulate Radio Communication" (), is a United States federal law which was the first legislation to require licenses for radio stations. It was enacted before the introduction of broadcasting to the general public, and was eventually found to contain insufficient authority to effectively control this new service, so the Act was replaced and the government's regulatory powers increased by the passage of the Radio Act of 1927. Background Radio communication (originally known as "wireless telegraphy") was developed in the late 1890s, but it was initially largely unregulated in the United States. The Wireless Ship Act of 1910 mandated that most passenger ships exiting U.S. ports had to carry radio equipment under the supervision of qualified operators, however individual stations remained unlicensed and unregulated. This led to numerous interference issues, including conflicts between amateur radio operators and the U.S. Navy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Edwin Kennelly
Arthur Edwin Kennelly (December 17, 1861 – June 18, 1939) was an American electrical engineer. Biography Kennelly was born December 17, 1861, in Colaba, in Bombay Presidency, British India, and was educated at University College School in London. He was the son of Irish naval officer Captain David Joseph Kennelly (1831–1907) and Catherine Gibson Heycock (1839–1863). His mother died when he was three years old. In 1863, his father retired from the navy and later Arthur and his father returned to England. In 1878, his father married Ellen L.Spencer and moved the family to Sydney, Nova Scotia, when he took over the Sydney and Louisbourg Coal and Railway Company Limited. By his father's third marriage, Arthur gained four half siblings, Zaida Kennelly in 1881, David J. Kennelly Jr. in 1882, Nell K. Kennelly in 1883, and Spencer M. Kennelly in 1885. Kennelly joined Thomas Edison's West Orange laboratory in December 1887, staying until March 1894. While there he had a role in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oliver Heaviside
Oliver Heaviside FRS (; 18 May 1850 – 3 February 1925) was an English self-taught mathematician and physicist who invented a new technique for solving differential equations (equivalent to the Laplace transform), independently developed vector calculus, and rewrote Maxwell's equations in the form commonly used today. He significantly shaped the way Maxwell's equations are understood and applied in the decades following Maxwell's death. His formulation of the telegrapher's equations became commercially important during his own lifetime, after their significance went unremarked for a long while, as few others were versed at the time in his novel methodology. Although at odds with the scientific establishment for most of his life, Heaviside changed the face of telecommunications, mathematics, and science. Biography Early life Heaviside was born in Camden Town, London, at 55 Kings Street (now Plender Street), the youngest of three children of Thomas, a draughtsman and wood ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glace Bay, Nova Scotia
Glace Bay (Scottish Gaelic: ''Glasbaidh'') is a community in the eastern part of the Cape Breton Regional Municipality in Nova Scotia, Canada. It forms part of the general area referred to as Industrial Cape Breton. Formerly an incorporated town (1901–1995), the municipal government in Glace Bay was dissolved and the community was amalgamated into the larger regional municipality. Prior to amalgamation, Glace Bay had been the province's fourth largest urban area and the largest town in Nova Scotia by population. Neighbouring communities include Reserve Mines, Dominion, and Tower Road. History As early as the 1720s, the French inhabited the area to supply Fortress of Louisbourg with coal. They named the location ''baie de Glace'' (literally, ''Bay of Ice'') because of the sea ice which filled the ocean each winter. In 1748, after the capture of Fortress Louisbourg, the British constructed Fort William at Table Head in order to protect a mine that produced coal to supply the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jack Belrose
John S. (Jack) Belrose (born 24 November 1926), is a Canadian radio scientist. He was born in the small town of Warner, Alberta. He attended the University of Cambridge, where he was awarded a PhD in 1958. He has worked for the Defence Research Telecommunications Establishment (DRTE) for 33 years. He is a member of the Canadian Amateur Radio Hall of Fame and, along with Walter Cronkite Walter Leland Cronkite Jr. (November 4, 1916 – July 17, 2009) was an American broadcast journalist who served as anchorman for the ''CBS Evening News'' for 19 years (1962–1981). During the 1960s and 1970s, he was often cited as "the mo ..., was awarded the Radio Club of America's Armstrong Medal on 16 November 2007. References External linksRemembrances of a Radio Scientist- Belrose's report on his 50th anniversary of working in the field of radio science.- a paper by Jack Belrose. 1926 births Possibly living people Canadian engineers Alumni of the University of Cambridge Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse Code
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of the inventors of the telegraph. International Morse code encodes the 26 basic Latin letters through , one accented Latin letter (), the Arabic numerals, and a small set of punctuation and procedural signals ( prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration is the basic unit of time measurement in Morse code transmission. The duration of a ''dah'' is three times the duration of a ''dit''. Each ''dit'' or ''dah'' within an encoded character is followed by a period of signal absence, called a ''space'', equal to the ''dit'' duration. The letters of a word are separated by a space of duration equal to three ''dits' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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