|
Alexanderson Radio Alternator
An Alexanderson alternator is a rotating machine invented by Ernst Alexanderson in 1904 for the generation of high-frequency alternating current for use as a radio transmitter. It was one of the first devices capable of generating the continuous radio waves needed for transmission of amplitude modulated signals by radio. It was used from about 1910 in a few "superpower" longwave radiotelegraphy stations to transmit transoceanic message traffic by Morse code to similar stations all over the world. Although superceded in the early 1920s by the development of vacuum-tube transmitters, the Alexanderson alternator continued to be used until World War II. It is on the list of IEEE Milestones as a key achievement in electrical engineering. History Prior developments After radio waves were discovered in 1887, the first generation of radio transmitters, the spark gap transmitters, produced strings of ''damped waves'', pulses of radio waves which died out to zero quickly. By ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexanderson Alternator
An Alexanderson alternator is a rotating machine invented by Ernst Alexanderson in 1904 for the generation of high-frequency alternating current for use as a radio transmitter. It was one of the first devices capable of generating the continuous radio waves needed for transmission of amplitude modulated signals by radio. It was used from about 1910 in a few "superpower" longwave radiotelegraphy stations to transmit transoceanic message traffic by Morse code to similar stations all over the world. Although superceded in the early 1920s by the development of vacuum-tube transmitters, the Alexanderson alternator continued to be used until World War II. It is on the list of IEEE Milestones as a key achievement in electrical engineering. History Prior developments After radio waves were discovered in 1887, the first generation of radio transmitters, the spark gap transmitters, produced strings of '' damped waves'', pulses of radio waves which died out to zero quickly. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damped Wave (radio Transmission)
A damped wave was an early method of radio transmission produced by the first radio transmitters ( spark gap transmitters) which consisted of a series of damped radio waves. Information was carried on this signal by telegraphy, turning the transmitter on and off ( on-off keying) to send messages in Morse code. Damped waves were the first practical means of radio communication, used during the wireless telegraphy era which ended around 1920. In radio engineering it is now generally referred to as "Class B" emission. Such transmissions have a wide bandwidth and generate electrical "noise" (electromagnetic interference) which interferes with other radio transmissions. Because of their potential to cause interference and their resulting wasteful use of radio spectrum resources, there is an international prohibition against the use of class B damped wave radio emissions (except in the USA under Part 15: "§15.521 Technical requirements applicable to all UWB devices. (i) The pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Hays Hammond, Jr
John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second Epistle of John, often shortened to 2 John * Third Epistle of John, often shortened to 3 John People * John the Baptist (died c. AD 30), regarded as a prophet and the forerunner of Jesus Christ * John the Apostle (lived c. AD 30), one of the twelve apostles of Jesus * John the Evangelist, assigned author of the Fourth Gospel, once identified with the Apostle * John of Patmos, also known as John the Divine or John the Revelator, the author of the Book of Revelation, once identified with the Apostle * John the Presbyter, a figure either identified with or distinguished from the Apostle, the Evangelist and John of Patmos Other people with the given name Religious figures * John, father of Andrew the Apostle and Saint Peter * Pope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brant Rock, Massachusetts
Ocean Bluff-Brant Rock is a census-designated place (CDP) in Plymouth County, Massachusetts, United States, composed of the neighborhoods of Ocean Bluff, Brant Rock, Fieldston, and Rexhame in the town of Marshfield. The population of the CDP was 4,970 at the 2010 census. History Brant Rock and Ocean Bluff were originally inhabited by Native Americans, including members of the Wampanoag tribe of the Algonquian peoples. Native American artifacts have been found extensively in the area. The main road through the area, known today as Ocean Street, is a Native American road, likely very ancient. The area at the end of Brant Rock village, known as Blackman's Point, was a Native American campground. In the 1630s, the government of the Pilgrim settlers at Plymouth began to give out land grants in the area. The Ocean Bluff area was first granted to the governor of the Pilgrims. It was known by about 1638 as "Governor's Island.” Later on in the 17th century, it became known as " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Communication
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Electric
General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energy, digital industry, additive manufacturing and venture capital and finance, but has since divested from several areas, now primarily consisting of the first four segments. In 2020, GE ranked among the Fortune 500 as the 33rd largest firm in the United States by gross revenue. In 2011, GE ranked among the Fortune 20 as the 14th most profitable company, but later very severely underperformed the market (by about 75%) as its profitability collapsed. Two employees of GE – Irving Langmuir (1932) and Ivar Giaever (1973) – have been awarded the Nobel Prize. On November 9, 2021, the company announced it would divide itself into three investment-grade public companies. On July 18, 2022, GE unveiled the brand names of the companies it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reginald Fessenden
Reginald Aubrey Fessenden (October 6, 1866 – July 22, 1932) was a Canadian-born inventor, who did a majority of his work in the United States and also claimed U.S. citizenship through his American-born father. During his life he received hundreds of patents in various fields, most notably ones related to radio and sonar. Fessenden is best known for his pioneering work developing radio technology, including the foundations of amplitude modulation (AM) radio. His achievements included the first transmission of speech by radio (1900), and the first two-way radiotelegraphic communication across the Atlantic Ocean (1906). In 1932 he reported that, in late 1906, he also made the first radio broadcast of entertainment and music, although a lack of verifiable details has led to some doubts about this claim. Early years Reginald Fessenden was born October 6, 1866, in East Bolton, Quebec, the eldest of the Reverend Elisha Joseph Fessenden and Clementina Trenholme's four children. Elisha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elihu Thomson
Elihu Thomson (March 29, 1853 – March 13, 1937) was an English-born American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France. Early life He was born in Manchester, England, on March 29, 1853, but his family moved to Philadelphia in the United States in 1858. and Thomson attended Central High School in Philadelphia and graduated in 1870. Thomson took a teaching position at Central, and in 1876, at the age of twenty-three, held the chair of Chemistry. In 1880, he left Central to pursue research in the emerging field of electrical engineering. Electrical innovations With Edwin J. Houston, a former teacher and later colleague of Thomson's at Central High School, Thomson founded the Thomson-Houston Electric Company. Notable inventions created by Thomson during this period include an arc-lighting system, an automatically regulated three-coil dynamo, a magnetic lightning arrester, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frederick Thomas Trouton
Frederick Thomas Trouton FRS (; 24 November 1863 – 21 September 1922) was an Irish physicist known for Trouton's rule and experiments to detect the Earth's motion through the luminiferous aether. Life and work Trouton was born in Dublin on 24 November 1863, the youngest son of the wealthy and prominent Thomas Trouton. He attended Royal School Dungannon and went on to Trinity College, Dublin in 1884, where he studied engineering and physical science. While still an undergraduate student, Trouton observed a relationship between boiling points and energies of vaporisations, which he presented in two short papers. He found the change of entropy per mole for vaporisation at a boiling point is constant, or expressed mathematically ΔSm,vap = 10.5 R (where R is the ideal gas constant). This became known as Trouton's rule and, despite having some exceptions, is used to estimate the enthalpy of vaporisation of liquids whose boiling points are known. Trouton himself belittled h ... [...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 transmitt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
