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Duplexer
A duplexer is an electronic device that allows bi-directional ( duplex) communication over a single path. In radar and radio communications systems, it isolates the receiver from the transmitter while permitting them to share a common antenna. Most radio repeater systems include a duplexer. Duplexers can be based on frequency (often a waveguide filter), polarization (such as an orthomode transducer), or timing (as is typical in radar). Types Transmit-receive switch In radar, a transmit/receive (TR) switch alternately connects the transmitter and receiver to a shared antenna. In the simplest arrangement, the switch consists of a gas-discharge tube across the input terminals of the receiver. When the transmitter is active, the resulting high voltage causes the tube to conduct, shorting together the receiver terminals to protect it, while its complementary, the anti-transmit/receive (ATR) switch, is a similar discharge tube which decouples the transmitter from the antenna whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sutton Tube
Sutton tube was the name given to the first reflex klystron, developed in 1940 by Robert W. Sutton of Signal School group at the Bristol University. The Sutton tube was developed as a local oscillator for the receiver of 10cm microwave radar sets. Due to its geometry and long drift space, it suffered from mode jumping through the tuning range. For this reason, from late 1941 onward, it was replaced in many sets by the Western Electric 707A (also known as McNally tube, named by its developer). The reflex klystron is a type of vacuum tube used to generate microwaves. It is a low-power device used primarily for two purposes: one is to provide a tuneable low-power frequency source for the local oscillators in receiver circuits, and the other, with minor modifications, as a switch that could turn on and off another microwave source. The second use, sometimes known as a soft Sutton tube or rhumbatron switch, was a key component in the development of microwave radar by United Kingdom, B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duplex (telecommunications)
A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow for simultaneous communication in both directions between two connected parties or to provide a reverse path for the monitoring and remote adjustment of equipment in the field. There are two types of duplex communication systems: full-duplex (FDX) and half-duplex (HDX). In a full-duplex system, both parties can communicate with each other simultaneously. An example of a full-duplex device is plain old telephone service; the parties at both ends of a call can speak and be heard by the other party simultaneously. The earphone reproduces the speech of the remote party as the microphone transmits the speech of the local party. There is a two-way communication channel between them, or more strictly speaking, there are two communication channel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Repeater
A radio repeater is a combination of a radio receiver and a radio transmitter that receives a signal and retransmits it, so that two-way radio signals can cover longer distances. A repeater sited at a high elevation can allow two mobile stations, otherwise out of line-of-sight propagation range of each other, to communicate. Repeaters are found in professional, commercial, and government mobile radio systems and also in amateur radio. Repeater systems use two different radio frequencies; the mobiles transmit on one frequency, and the repeater station receives those transmission and transmits on a second frequency. Since the repeater must transmit at the same time as the signal is being received, and may even use the same antenna for both transmitting and receiving, frequency-selective filters are required to prevent the receiver from being overloaded by the transmitted signal. Some repeaters use two different frequency bands to provide isolation between input and output or as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Union
The Western Union Company is an American multinational financial services corporation headquartered in Denver, Denver, Colorado. Founded in 1851 as the New York and Mississippi Valley Printing Telegraph Company in Rochester, New York, the company changed its name to the Western Union Telegraph Company in 1856 after merging with several other telegraph companies. It dominated the American telegraphy industry from the 1860s to the 1980s, pioneering technology such as telex and developing a range of telegraph-related services, including wire transfer, wire money transfer, in addition to its core business of transmitting and delivering telegram messages. After experiencing financial difficulties, it began to move its business away from communications in the 1980s and increasingly focused on its money-transfer services. It ceased its communications operations completely in 2006, at which time ''The New York Times'' described it as "the world's largest money-transfer business" and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas Edison
Thomas Alva Edison (February11, 1847October18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, which include the phonograph, the motion picture camera, and early versions of the electric Incandescent light bulb, light bulb, have had a widespread impact on the modern industrial society, industrialized world. He was one of the first inventors to apply the principles of organized science and teamwork to the process of invention, working with many researchers and employees. He established the first industrial research laboratory. Edison was raised in the American Midwest. Early in his career he worked as a telegraph operator, which inspired some of his earliest inventions. In 1876, he established his first laboratory facility in Menlo Park, New Jersey, where many of his early inventions were developed. He later established a botanical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadruplex Telegraph
The Quadruplex telegraph is a type of electrical telegraph which allows a total of four separate signals to be transmitted and received on a single wire at the same time (two signals in each direction). Quadruplex telegraphy thus implements a form of multiplexing. The technology was invented by Thomas Edison, who sold the rights to Jay Gould, the owner of the Atlantic and Pacific Telegraph Company, in 1874 for the sum of $30,000 (). Edison had previously been turned down by Western Union for the sale of the Quadruplex. This proved to be a grave mistake. Jay Gould used the Quadruplex to wage price wars on Western Union and to short its stock. Cornelius Vanderbilt was Western Union's largest shareholder and caught the brunt of Jay Gould's move. Vanderbilt died during the saga, which left his son William in charge. William Vanderbilt, much like his father, was no match for Jay Gould and quickly buckled. To stop the rate war Western Union bought Atlantic Pacific (and the rights t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Barker Stearns
Joseph Barker Stearns (1831-1895) was the inventor of the duplex system of telegraphy. Biography Stearns was the son of Edward Ray and Eliza Tyler Barker Stearns of Weld, Maine. As a youth, he worked on a farm. He studied telegraphy at Newburyport, Massachusetts, where he became manager of the office. From 1855 to 1869, he was superintendent of the Fire Alarm Telegraph Company of Boston, Massachusetts and was the first to take out patents on the use of reversed currents in connection with the fire alarm signal system. He was president of Franklin Telegraph Co., from 1869 to 1871, during which time he invented the first practical system of duplex telegraphy which was successfully applied to the English, French and Belgian lines. Two years later this system was used for the Atlantic cables. He sold rights under his duplex patents to the Western Union Telegraph and Cable Companies, receiving large royalties for the use of his inventions from governments in England, France, Ital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siemens & Halske
Siemens & Halske AG (or Siemens-Halske) was a German electrical engineering company that later became part of Siemens. It was founded on 12 October 1847 as ''Telegraphen-Bauanstalt von Siemens & Halske'' by Werner von Siemens and Johann Georg Halske. The company, located in Berlin-Kreuzberg, specialised in manufacturing electrical telegraphs according to Charles Wheatstone's patent of 1837. In 1848, the company constructed one of the first European telegraph lines from Berlin to Frankfurt am Main. Siemens & Halske was not alone in the realm of electrical engineering. In 1887, Emil Rathenau had established '' Allgemeine Elektrizitäts-Gesellschaft'' (AEG), which became a long-time rival. In 1881, Siemens & Halske built the Gross-Lichterfelde Tramway, the world's first electric streetcar line, in the southwestern Lichterfelde suburb of Berlin, followed by the Mödling and Hinterbrühl Tram near Vienna, the first electrical interurban tram in Austria-Hungary. 1882 saw the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Julius Wilhelm Gintl
Julius Wilhelm Gintl (November 12, 1804 – December 22, 1883) was an Austrian physicist. Biography Gintl was born in 1804 in Prague and attended university in his hometown. He was chair of physics at Vienna University and later at Gratz. In 1847, the Austrian government commissioned him to manage the introduction of the electrical telegraph. In 1853, Gintl developed an early form of duplex electrical telegraph, which allowed two messages to be transmitted on a single wire in opposite directions. This duplex communication was an early specific case of the general practice of multiplexing. While Gintl's technology was not commercial successful, his method was improved upon by German engineer Carl Frischen and later by J. B. Stearns, who would patent a version in 1872. Edison, who was also working on the design, would further refine his method in his implementation of a quadruplex telegraph The Quadruplex telegraph is a type of electrical telegraph which allows a total o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Telegraph
Electrical telegraphy is Point-to-point (telecommunications), point-to-point distance communicating via sending electric signals over wire, a system primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called ''telegraphs'', that were devised to send text messages more quickly than physically carrying them. Electrical telegraphy can be considered the first example of electrical engineering. Electrical telegraphy consisted of two or more geographically separated stations, called telegraph offices. The offices were connected by wires, usually supported overhead on utility poles. Many electrical telegraph systems were invented that operated in different ways, but the ones that became widespread fit into two broad categories. First are the needle telegraphs, in which electric current sent down the telegraph line produces electromagnetic force to move a needle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Standard 1037C
Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. This document provides federal departments and agencies a comprehensive source of definitions of terms used in telecommunications and directly related fields by international and U.S. government telecommunications specialists. As a publication of the U.S. government, prepared by an agency of the U.S. government, it appears to be mostly available as a public domain resource, but a few items are derived from copyrighted sources: where this is the case, there is an attribution to the source. This standard was superseded in 2001 by American National Standard T1.523-2001, Telecom Glossary 2000, which is published by ATIS. The old standard is still frequently used, because the new standard is protected by copyright, as usual f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
