Misplaced Pages

#691308

107-458: Trans Canada Microwave or Trans-Canada Skyway was a microwave relay system built in the 1950s to carry telephone and television signals from Canada's east coast to its west coast. Built across the nation, the towers ranged in height from nine metres high, to one in northern Ontario that was over 100 metres high. The system included 139 towers spanning over 6,275 kilometres and cost $ 50 million (equivalent to $ 531,000,000 in 2023). Canada

214-487: A $ 39 billion stock and cash offer. The bid was withdrawn after the takeover company was faced with significant regulatory and legal hurdles, along with heavy resistance from the U.S. government. As per the original acquisition agreement, T-Mobile received $ 3 billion in cash as well as access to $ 1 billion worth of AT&T-held wireless spectrum. In September 2013, AT&T announced it would expand into Latin America through

321-419: A beam of radio waves in the microwave frequency range to transmit video , audio , or data between two locations, which can be from just a few feet or meters to several miles or kilometers apart. Microwave links are commonly used by television broadcasters to transmit programmes across a country, for instance, or from an outside broadcast back to a studio. Mobile units can be camera mounted, allowing cameras

428-589: A collaboration with América Móvil . In December 2013, AT&T announced plans to sell its Connecticut wireline operations to Stamford-based Frontier Communications . AT&T acquired BellSouth Corporation on December 29, 2006, following FCC approval. The transaction consolidated ownership and management of Cingular Wireless. AT&T rebranded its wireless retail stores from Cingular to AT&T in January 2007. In late 2014, AT&T purchased Mexican cellular carrier Iusacell , and two months later, it purchased

535-528: A connection between New York City and Murray Hill, the location of Bell Laboratories in 1946. The TDX system was set up between New York and Boston in 1947. The TDX was upgraded to the TD2 system, which used [the Morton tube, 416B and later 416C, manufactured by Western Electric] in the transmitters, and then later to TD3 that used solid-state electronics . Remarkable were the microwave relay links to West Berlin during

642-419: A diameter of up to 4 m (13 ft). Highly directive antennas permit an economical use of the available frequency spectrum, despite long transmission distances. Because of the high frequencies used, a line-of-sight path between the stations is required. Additionally, in order to avoid attenuation of the beam, an area around the beam called the first Fresnel zone must be free from obstacles. Obstacles in

749-413: A distance of 56 km (35 miles), was followed in 1935 by a 300 MHz telecommunication link, the first commercial microwave relay system. The development of radar during World War II provided much of the microwave technology which made practical microwave communication links possible, particularly the klystron oscillator and techniques of designing parabolic antennas. Though not commonly known,

856-488: A few kilometers, not enough for long-distance communication. The electronic technologies needed in the millimeter wave band are also in an earlier state of development than those of the microwave band. More recently, microwaves have been used for wireless power transmission . Microwave radio relay is a technology widely used in the 1950s and 1960s for transmitting information, such as long-distance telephone calls and television programs between two terrestrial points on

963-493: A lawsuit for the United States Department of Justice Antitrust Division to block the merger with Time Warner, saying it "will harm competition, result in higher bills for consumers and less innovation." On June 12, 2018, U.S. District Court Judge Richard J. Leon ruled that the merger could go forward. The merger closed two days afterwards, with Time Warner becoming a wholly owned subsidiary of AT&T. A day later,

1070-530: A line of sight limits the separation between stations to the visual horizon, about 30 to 50 miles (48 to 80 km). For longer distances, the receiving station could function as a relay, retransmitting the received information to another station along its journey. Chains of microwave relay stations were used to transmit telecommunication signals over transcontinental distances. Microwave relay stations were often located on tall buildings and mountaintops, with their antennas on towers to get maximum range. Beginning in

1177-569: A lower cost per bit. During the Cold War, the US intelligence agencies, such as the National Security Agency (NSA), were reportedly able to intercept Soviet microwave traffic using satellites such as Rhyolite/Aquacade . Much of the beam of a microwave link passes the receiving antenna and radiates toward the horizon, into space. By positioning a geosynchronous satellite in the path of the beam,

SECTION 10

#1733202938692

1284-470: A microwave frequency switch that allowed the same antennas to be used for broadcast or reception depending on the immediate needs of the network. The first links in Ontario and Quebec were within areas served entirely by Bell, but this was not the case for the rest of the network, where smaller regional telephone companies held local monopolies. This required additional planning, including deciding how to split up

1391-487: A narrow beam of microwaves. In microwave radio relay, a microwave transmitter and directional antenna transmits a narrow beam of microwaves carrying many channels of information on a line of sight path to another relay station where it is received by a directional antenna and receiver, forming a fixed radio connection between the two points. The link was often bidirectional, using a transmitter and receiver at each end to transmit data in both directions. The requirement of

1498-472: A separate entity, selling a 30% stake to TPG Capital (owners of Astound Broadband cable), while retaining a 70% stake in the new standalone company. The deal was closed on August 2, 2021. On May 17, 2021, AT&T announced plans to relinquish its equity interest in WarnerMedia , and have it merge with Discovery, Inc. in a US$ 43 billion deal to establish a new media company. Electronic Arts , which

1605-442: A specialty option. On April 24, 2020, AT&T announced that effective July 1, 2020, company COO John Stankey would replace Randall L. Stephenson as CEO of AT&T. It was also acknowledged that AT&T's acquisitions of DirecTV and Time Warner had by this point resulted in a massive debt burden of $ 200 billion for the company. As a result of planned cost cutting programs, the sale of Warner Bros. Interactive Entertainment

1712-449: A time, these networks were also used to send television signals for cross-country broadcast, and later, computer data. Communication satellites took over the television broadcast market during the 1970s and 80s, and the introduction of long-distance fibre optic systems in the 1980s and especially 90s led to the rapid rundown of the relay networks, most of which are abandoned. In recent years, there has been an explosive increase in use of

1819-617: A wholly owned subsidiary of AT&T Inc. Cingular was then rebranded as AT&T Mobility . AT&T Inc. also acquired Time Warner in 2016, with the proposed merger confirmed on June 12, 2018 and the aim of making AT&T Inc. the largest and controlling shareholder of Time Warner, which it then rebranded as WarnerMedia in 2018. The company later withdrew its equity stake in WarnerMedia in 2022 and merged it with Discovery, Inc. to create Warner Bros. Discovery , divesting itself of its media arm. The current AT&T reconstitutes most of

1926-408: Is regulated by International Telecommunication Union ( ITU-R ) and local regulations ( ETSI , FCC ). In the last decade the dedicated spectrum for each microwave band has become extremely crowded, motivating the use of techniques to increase transmission capacity such as frequency reuse, polarization-division multiplexing , XPIC , MIMO . The history of radio relay communication began in 1898 with

2033-544: The Washington Post on May 10 confirmed the figure of 12 payments, which had begun three days after the President was sworn into office . AT&T confirmed the report the same day. The report from The Washington Post , as well as additional reporting from Bloomberg , revealed the payments had been made for Cohen to "provide guidance" relating to the attempted $ 85 billion merger with Time Warner , to gain information on

2140-640: The American Telephone and Telegraph Company , is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas , Texas . It is the world's third largest telecommunications company by revenue and the third largest wireless carrier in the United States behind Verizon and T-Mobile . As of 2023, AT&T was ranked 13th on the Fortune 500 rankings of

2247-694: The Asia Pacific ; its regional headquarters is located in Hong Kong. The company is also active in Mexico, and on November 7, 2014, it was announced that Mexican carrier Iusacell would be acquired by AT&T. The acquisition was approved in January 2015. On April 30, 2015, AT&T acquired wireless operations Nextel Mexico from NII Holdings (now AT&T Mexico). AT&T's current board of directors as of March 2024: The current management as of March 2024 includes: According to OpenSecrets , AT&T

SECTION 20

#1733202938692

2354-525: The Baby Bells , Ameritech sold some of its Wisconsin landlines to CenturyTel , in 1998; BellSouth sold some of its lines to MebTel, during the 2000s; US West sold many historically Bell landlines to Lynch Communications and Pacific Telecom , in the 1990s; Verizon sold many of its New England lines to FairPoint in 2008, and its West Virginia operations to Frontier Communications in 2010. On October 25, 2014, Frontier Communications took over control of

2461-467: The Bell Labs TD-2 system, built locally by Northern Electric , operating at base frequency of 4 GHz. It could carry twelve 10 MHz wide signals, producing six channels in both directions. In US service at that time, any one channel carried one television channel or up to 600 telephone conversations encoded using frequency division multiplexing (FDM). Bell upgraded their systems to add FDM to

2568-554: The Cold War , which had to be built and operated due to the large distance between West Germany and Berlin at the edge of the technical feasibility. In addition to the telephone network, also microwave relay links for the distribution of TV and radio broadcasts. This included connections from the studios to the broadcasting systems distributed across the country, as well as between the radio stations, for example for program exchange. Military microwave relay systems continued to be used into

2675-483: The English Channel using 10-foot (3 m) dishes. Telephony, telegraph, and facsimile data was transmitted over the bidirectional 1.7 GHz beams 40 miles (64 km) between Dover , UK, and Calais , France. The radiated power, produced by a miniature Barkhausen–Kurz tube located at the dish's focus, was one-half watt. A 1933 military microwave link between airports at St. Inglevert, France, and Lympne, UK,

2782-807: The Kingsbury Commitment , throughout most of the twentieth century. This monopoly was known as the Bell System , and during this period, AT&T was also known by the nickname Ma Bell . In 1982, U.S. regulators broke up the AT&;T monopoly , requiring AT&T to divest its local subsidiaries, which it did by grouping them into seven individual companies. These new companies were known as Regional Bell Operating Companies, or more informally, Baby Bells. AT&T continued to operate long-distance services but faced increasing competition from competitors such as MCI and Sprint . Southwestern Bell Corporation (SBC)

2889-400: The U.S. Federal Communications Commission (FCC) follows in its rulemaking processes. The FCC would have to act in a more transparent way as a result of this bill, forced to accept public input about regulations. AT&T's Executive Vice President of Federal Relations, Tim McKone, said that the bill's "much needed institutional reforms will help arm the agency with the tools to keep pace with

2996-538: The line of sight . This was sometimes done from a helicopter . The towers themselves were sized to the local terrain, with the largest, just over 350 feet (110 m) high, outside North Bay . SaskTel was the first regional carrier to complete their assigned section of the system, which went operational in 1957. The entire system carried its first signals on 18 June 1958, and was declared officially operational on 1 July, Dominion Day . Stretching 6,400 km from Sydney, Nova Scotia to Victoria, British Columbia , it

3103-400: The 1950s a unit of the US telephone carrier, AT&T Long Lines , built a transcontinental system of microwave relay links across the US which grew to carry the majority of US long distance telephone traffic, as well as television network signals. The main motivation in 1946 to use microwave radio instead of cable was that a large capacity could be installed quickly and at less cost. It

3210-611: The 1950s, networks of microwave relay links, such as the AT&;T Long Lines system in the U.S., carried long-distance telephone calls and television programs between cities. The first system, dubbed TDX and built by AT&T, connected New York and Boston in 1947 with a series of eight radio relay stations. Through the 1950s, they deployed a network of a slightly improved version across the U.S., known as TD2 . These included long daisy-chained links that traversed mountain ranges and spanned continents. The launch of communication satellites in

3317-485: The 1960s, when many of these systems were supplanted with tropospheric scatter or communication satellite systems. When the NATO military arm was formed, much of this existing equipment was transferred to communications groups. The typical communications systems used by NATO during that time period consisted of the technologies which had been developed for use by the telephone carrier entities in host countries. One example from

Trans Canada Microwave - Misplaced Pages Continue

3424-411: The 1970s provided a cheaper alternative. Much of the transcontinental traffic is now carried by satellites and optical fibers , but microwave relay remains important for shorter distances. Because in microwave transmission the waves travel in narrow beams confined to a line-of-sight path from one antenna to the other, they do not interfere with other microwave equipment, so nearby microwave links can use

3531-406: The 1990s. Frequency bands below 10 GHz, and above all, the information to be transmitted, were a stream containing a fixed capacity block. The target was to supply the requested availability for the whole block ( Plesiochronous digital hierarchy , PDH, or synchronous digital hierarchy , SDH). Fading and/or multipath affecting the link for short time period during the day had to be counteracted by

3638-640: The 20th century, AT&T had a monopoly on phone service in the United States. The company was formally rebranded as AT&T Corporation in 1994. The 1982 United States v. AT&T antitrust lawsuit resulted in the divestiture of AT&T's ("Ma Bell") local operating subsidiaries which were grouped into seven Regional Bell Operating Companies (RBOCs), commonly referred to as "Baby Bells", resulting in seven independent companies, including Southwestern Bell Corporation (SBC). The latter changed its name to SBC Communications Inc. in 1995. In 2005, SBC purchased its former parent AT&T Corp. and took on

3745-619: The AT&T landline network in Connecticut after being approved by state utility regulators. The deal was worth about $ 2 billion, and included Frontier inheriting about 2,500 of AT&T's employees and many of AT&T's buildings. The company is headquartered at Whitacre Tower in downtown Dallas, Texas. On June 27, 2008, AT&T announced that it would move its corporate headquarters from downtown San Antonio to One AT&T Plaza in downtown Dallas. The company said that it moved to gain better access to its customers and operations throughout

3852-579: The British Army used the Wireless Set Number 10 in this role during World War II. The need for radio relay did not really begin until the 1940s exploitation of microwaves , which traveled by line of sight and so were limited to a propagation distance of about 40 miles (64 km) by the visual horizon. After the war, telephone companies used this technology to build large microwave radio relay networks to carry long-distance telephone calls. During

3959-495: The CBC network, plans began for the first major link from Toronto to Montreal via Ottawa . After discussions between Bell's president Thomas Wardrope Eadie and CBC's president Alphonse Ouimet , the network would also include a link to Buffalo, New York , to allow US television programming to be rebroadcast into the Toronto market. The link went live on 15 January 1953, and the rest of

4066-568: The Caribbean under the Vrio brand; and Advertising and Analytics, since renamed Xandr . On July 13, 2017, it was reported that AT&T would introduce a cloud-based DVR streaming service. It hoped to create a unified platform across DirecTV and its DirecTV Now streaming service, with U-verse to be added shortly afterward. The service, named HBO Max , launched in May 2020. On September 12, 2017, it

4173-484: The IPO due to market conditions. As of 2019, AT&T is the world's largest telecommunications company. AT&T is also the largest provider of mobile telephone services and the largest provider of fixed telephone (landline) services in the United States. In September 2019, activist investor Elliott Management revealed that it had purchased $ 3.2 billion of AT&T stock (a 1.2% equity interest), and had pushed for

4280-567: The Internet speed of today's marketplace. It will also ensure that outmoded regulatory practices for today's competitive marketplace are properly placed in the dustbin of history." In May 2018, reports emerged that AT&T made 12 monthly payments between January and December 2017 to Essential Consultants, a company set up by President Donald Trump 's lawyer Michael Cohen , totaling $ 600,000. Although initial reports on May 8 mentioned only four monthly payments totaling $ 200,000, documents obtained by

4387-590: The Mexican wireless business of NII Holdings . AT&T merged the two companies to create AT&T Mexico . In July 2015, AT&T purchased DirecTV for $ 48.5 billion. AT&T then announced plans to converge its existing U-verse home internet and IPTV brands with DirecTV , to create AT&T Entertainment . On October 22, 2016, AT&T announced a deal to buy Time Warner for $ 108.7 billion in an effort to increase its media holdings. On November 20, 2017, Assistant Attorney General Makan Delrahim filed

Trans Canada Microwave - Misplaced Pages Continue

4494-553: The Private Enterprise Board of the American Legislative Exchange Council (ALEC). ALEC is a nonprofit organization of conservative state legislators and private sector representatives that drafts and shares model state-level legislation for distribution among state governments in the United States. During the period of 1998 to 2019, the company expended US$ 380.1 million on lobbying in

4601-515: The TD-2 system, and able to cover all of Canada from a single satellite, Anik was much cheaper to operate in spite of the cost of launching the satellite to orbit. The original Aniks used the same 6 GHz frequencies as the TH system to make equipment interfacing easier, but the very low signal strengths from this pioneering satellite required large ground stations in remote locations to operate successfully. The network

4708-570: The Trump administration's planned tax reforms, as well as about potential changes to net neutrality policies under the new FCC. Chairman of the FCC Ajit Pai denied Cohen ever inquired about net neutrality on AT&T's behalf. A spokesperson for AT&T said that the company had been contacted by the Special Counsel investigation led by Robert Mueller regarding the payments, and had provided all

4815-759: The UK, the General Post Office (GPO). Bell argued to the Department of Transport that allowing CNCP to extend their network would lead to wasteful overcapacity, before then noting they were in the process of setting up their own second line anyway. Cabinet once again intervened in CNCP's favour. CNCP opened their new system between Montreal and Vancouver , the Transcontinental Microwave System, in late 1964. The system used AT&T's higher-capacity TH system which

4922-674: The US, and concluded a microwave relay was the solution for rapidly improving the number of connections in these markets. In 1952, the Canadian Broadcasting Corporation (CBC) issued a contract for a nationwide relay to send television and radio signals coast-to-coast. The contract was sent to both Bell and CNCP Telecommunications , the joint Canadian National Railway - Canadian Pacific Railway company that shared telegraph services. The Department of Transport , responsible for licensing bandwidth allocations in Canada, tried to have

5029-531: The USA is the RCA CW-20A 1–2 GHz microwave relay system which utilized flexible UHF cable rather than the rigid waveguide required by higher frequency systems, making it ideal for tactical applications. The typical microwave relay installation or portable van had two radio systems (plus backup) connecting two line of sight sites. These radios would often carry 24 telephone channels frequency-division multiplexed on

5136-519: The United States. A key political issue for AT&T has been the question of which businesses win the right to profit by providing broadband internet access in the United States. The company has also lobbied in support of several federal bills. AT&T supported the Federal Communications Commission Process Reform Act of 2013 (H.R. 3675; 113th Congress) , a bill that would make a number of changes to procedures that

5243-400: The area and reception issues arising from the use of nearby land (such as in manufacturing and forestry) are important issues to consider when planning radio links. In the planning process, it is essential that "path profiles" are produced, which provide information about the terrain and Fresnel zones affecting the transmission path. The presence of a water surface, such as a lake or river, along

5350-469: The better-known AT&T name and brand, with the original AT&T Corporation still existing as the long-distance landline subsidiary of the merged company. The current AT&T Inc. claims the original AT&T Corporation's history (dating to 1877) as its own, but retains SBC's pre-2005 corporate structure and stock price history. As well, all SEC filings before 2005 are under SBC, not AT&T. AT&T made an attempt in 2011 to purchase T-Mobile for

5457-658: The breach. AT&T was also reported to have been affected by a 2024 attack from the Salt Typhoon advanced persistent threat linked to the Chinese government . Of the eight companies that were part of the Breakup of the Bell System, these five are a part of the current AT&T: AT&T's wireline business provides services in 22 states. The following companies have become defunct or were sold under SBC/AT&T ownership: Of

SECTION 50

#1733202938692

5564-800: The company changed its name to SBC Communications Inc. In early 1997 C. Michael Armstrong was named CEO, and Armstrong appointed John Zeglis as president later in that same year. By 1998, the company was in the top 15 of the Fortune 500, and by 1999, when Zeglis assumed the positions of chairman and CEO of AT&T Wireless , AT&T was part of the Dow Jones Industrial Average (lasting through 2015). Zeglis ended his service as president of AT&T in 2001 and resigned from his positions in AT&T Wireless in 2004. On November 18, 2005, SBC Communications purchased its former parent, AT&T Corporation for $ 16 billion. After this purchase, SBC adopted

5671-402: The company is reported to shareholders on an annual basis and a matter of public record. Where performance has been restated, the most recent statement of performance from an annual report is used. AT&T reported Total CO2e emissions (Direct + Indirect) for the twelve months ending 31 December 2020 at 5,788 Kt (-737 /-11.3% y-o-y) and plans to reduce emissions by 63% by 2030 from

5778-421: The company to divest assets to improve its share value. On March 4, 2020, AT&T announced its intent to perform major cost-cutting moves, including cuts to capital investment, and plans to promote AT&T TV (which officially launched nationally on March 2) as its primary pay television service offering. AT&T stated it would still primarily promote DirecTV "where cable broadband is not prevalent", and as

5885-527: The company was renamed WarnerMedia. Three months after completing the acquisition, AT&T reorganized into four main units: Communications, including consumer and business wireline telephony, AT&T Mobility, and consumer entertainment video services; WarnerMedia, including Turner cable television networks, Warner Bros. film and television production, and HBO ; AT&T Latin America, consisting of wireless service in Mexico and video in Latin America and

5992-578: The costs and revenues. This was carried out within the Trans-Canada Telephone System company, which had formed to handle the same sorts of issues for land-line cost sharing and long-distance fees. Construction of the cross-country network began on 8 March 1955. The system required a total of 139 stations, spaced at an average of 25 miles (40 km). The stations in the original core typically used squared-off parabolic reflectors , while later additions used horn-reflector antennas . Sites in

6099-524: The data. Data rates were also much higher than available using modems, and customers could share a single time slot by agreeing to only use the line at certain times. On its commercial release in February 1973 it was given the name The Dataroute. The seeds of the demise of the network appeared in 1972 with the launch of Anik I , the world's first domestic geostationary communications satellite . Capable of carrying twelve television channels, compared to six for

6206-860: The detrimental factors mentioned in this section, collectively known as path loss , make it necessary to compute suitable power margins, in order to maintain the link operative for a high percentage of time, like the standard 99.99% or 99.999% used in 'carrier class' services of most telecommunication operators. The longest known microwave radio relay crosses the Red Sea with a 360 km (220 mi) hop between Jebel Erba (2,170 m (7,120 ft) a.s.l., 20°44′46.17″N 36°50′24.65″E  /  20.7461583°N 36.8401806°E  / 20.7461583; 36.8401806 , Sudan) and Jebel Dakka (2,572 m (8,438 ft) a.s.l., 21°5′36.89″N 40°17′29.80″E  /  21.0935806°N 40.2916111°E  / 21.0935806; 40.2916111 , Saudi Arabia). The link

6313-542: The diversity architecture. During 1990s microwave radio links begun widely to be used for urban links in cellular network . Requirements regarding link distance changed to shorter hops (less than 10 km (6.2 mi), typically 3 to 5 km (1.9 to 3.1 mi)), and frequency increased to bands between 11 and 43 GHz and more recently, up to 86 GHz (E-band). Furthermore, link planning deals more with intense rainfall and less with multipath, so diversity schemes became less used. Another big change that occurred during

6420-456: The east were relatively easy to locate as they were already heavily developed, but in northern Ontario and especially the Rocky Mountains , aerial surveys were used to pick likely spots. Once selected, a temporary tower made of aluminium would be manually lifted into place and a small circular reflector hoisted to test the link and find the minimum altitude that gave it a good signal. Getting

6527-462: The equipment into position could be an enormous task; in one case at Morrissey Ridge in British Columbia , it took two months to bulldoze a road to the proposed site. Given this sort of delay, a new system was created in which a single workman would travel to the site and alert the next tower he was in place using a walky talky , then used a mirror to reflect the sun onto the next station to test

SECTION 60

#1733202938692

6634-404: The first effective long-distance fibre optic cables in the 1970s. Although these required repeater stations every few kilometres, and thus were expensive to implement, they offered orders of magnitude more bandwidth than the microwave links. The first major all-fibre network was completed by SaskTel in 1984, with a total distance of 3,268 kilometres (2,031 mi) of lines linking 52 centres. By

6741-501: The former Bell System , and includes four of the seven "Baby Bells" along with the original AT&T Corp., including the long-distance division . AT&T was founded as Bell Telephone Company by Alexander Graham Bell , Thomas Watson and Gardiner Greene Hubbard after Bell's patenting of the telephone in 1875. By 1881, Bell Telephone Company had become the American Bell Telephone Company. One of its subsidiaries

6848-414: The freedom to move around without trailing cables. These are often seen on the touchlines of sports fields on Steadicam systems. Terrestrial microwave relay links are limited in distance to the visual horizon, a few tens of miles or kilometers depending on tower height. Tropospheric scatter ("troposcatter" or "scatter") was a technology developed in the 1950s to allow microwave communication links beyond

6955-510: The headquarters for AT&T Mobility, with significant offices in Redmond, Washington, the former home of AT&T Wireless . Bedminster, New Jersey, is the headquarters for the company's Global Business Services group and AT&T Labs and is where the original AT&T Corp. remains located. St. Louis continues as home to the company's Directory operations, AT&T Advertising Solutions . AT&T also offers services in many locations throughout

7062-453: The horizon, to a range of several hundred kilometers. The transmitter radiates a beam of microwaves into the sky, at a shallow angle above the horizon toward the receiver. As the beam passes through the troposphere a small fraction of the microwave energy is scattered back toward the ground by water vapor and dust in the air. A sensitive receiver beyond the horizon picks up this reflected signal. Signal clarity obtained by this method depends on

7169-666: The information requested in November and December 2017. In early 2019, the Democratic House Judiciary requested records related to the AT&T-Time Warner merger from the White House . While it has expressed support for LGBTQ causes, AT&T has also donated to sponsors of anti-transgender legislation in several US states, especially those predominantly Republican -governed, including Arkansas, Tennessee, North Carolina, Texas and Florida. The financial performance of

7276-524: The largest United States corporations, with revenues of $ 122.4 billion. The modern company to bear the AT&T name began its history as the American District Telegraph Company, formed in St. Louis in 1878. After expanding services to Arkansas , Kansas , Oklahoma and Texas through a series of mergers, it became Southwestern Bell Telephone Company in 1920, which was then a subsidiary of

7383-420: The last decade was an evolution toward packet radio transmission. Therefore, new countermeasures, such as adaptive modulation , have been adopted. The emitted power is regulated for cellular and microwave systems. These microwave transmissions use emitted power typically from 0.03 to 0.30 W, radiated by a parabolic antenna on a narrow beam diverging by a few degrees (1 to 3-4). The microwave channel arrangement

7490-543: The late 1980s, fibre was being installed around the world, and by the 1990s any traffic formerly carried by the Skyway was moving to fibre. Microwave radio relay Although an experimental 40-mile (64 km) microwave telecommunication link across the English Channel was demonstrated in 1931, the development of radar in World War II provided the technology for practical exploitation of microwave communication. During

7597-411: The latter's branding, history, and stock trading symbol, as well as a version of its iconic logo. The merged entity, naming itself AT&T Inc., launched on December 30, 2005. The newly merged and renamed AT&T Inc. acquired BellSouth Corporation in 2006, the last independent Baby Bell, making the two companies' joint venture Cingular Wireless (which had itself acquired AT&T Wireless in 2004)

7704-514: The microwave band has a bandwidth 30 times that of all the rest of the radio spectrum below it. A disadvantage is that microwaves are limited to line of sight propagation; they cannot pass around hills or mountains as lower frequency radio waves can. Microwave radio transmission is commonly used in point-to-point communication systems on the surface of the Earth, in satellite communications , and in deep space radio communications . Other parts of

7811-412: The microwave beam can be received. At the turn of the 21 century, microwave radio relay systems were used increasingly in portable radio applications. The technology is particularly suited to this application because of lower operating costs, a more efficient infrastructure , and provision of direct hardware access to the portable radio operator. A microwave link is a communications system that uses

7918-438: The microwave carrier (i.e. Lenkurt 33C FDM). Any channel could be designated to carry up to 18 teletype communications instead. Similar systems from Germany and other member nations were also in use. Long-distance microwave relay networks were built in many countries until the 1980s, when the technology lost its share of fixed operation to newer technologies such as fiber-optic cable and communication satellites , which offer

8025-458: The microwave radio band are used for radars , radio navigation systems, sensor systems, and radio astronomy . The next higher frequency band of the radio spectrum , between 30 GHz and 300 GHz, are called " millimeter waves " because their wavelengths range from 10 mm to 1 mm. Radio waves in the millimeter wave band are strongly attenuated by the gases of the atmosphere , which limits their practical transmission distance to

8132-570: The microwave spectrum by new telecommunication technologies such as wireless networks , and direct-broadcast satellites which broadcast television and radio directly into consumers' homes. Larger line-of-sight links are once again popular for handing connections between mobile telephone towers, although these are generally not organized into long relay chains. Microwaves are widely used for point-to-point communications because their small wavelength allows conveniently-sized antennas to direct them in narrow beams, which can be pointed directly at

8239-509: The network to Montreal was completed in May the same year. The network was extended to Quebec City the next year, with branch links northward from the mainline to Peterborough and Barrie , and a short link southward to Kingston . The obvious value of the system, especially the Toronto-Montreal link, led Eadie to consider expanding the network into a trans-Canada system carrying television, teletype and telephone signals. The network used

8346-490: The original American Telephone & Telegraph Company . The latter was a successor of the original Bell Telephone Company founded by Alexander Graham Bell in 1877. The American Bell Telephone Company formed the American Telephone and Telegraph Company (AT&T) subsidiary in 1885. In 1899, AT&T became the parent company after the American Bell Telephone Company sold its assets to its subsidiary. During most of

8453-544: The original network grew, Bell carried through on their own plans and built a second Skyway using the same TH system as the CNCP lines. In 1972, the network was upgraded with new digital routers , initially tested on the Ottawa-Montreal route, soon added in Edmonton and Calgary, and then expanded across the country. Customers sent data into the system using local leased lines or short-range microwave relay at 50 kbps which

8560-617: The other. During the 1950s, CNCP concentrated on building a network in the more highly populated section of Canada, mostly in the area between Montreal and Toronto. This changed in 1962 when the CNCP received a contract from the Canadian Overseas Telecommunications Corporation (COTC) to build a second nationwide microwave relay system. COTC, a crown corporation , had formed to operate the CANTAT trans-Atlantic telephone cable in partnership with their counterparts in

8667-416: The path also must be taken into consideration since it can reflect the beam, and the direct and reflected beam can interfere with each other at the receiving antenna, causing multipath fading. Multipath fades are usually deep only in a small spot and a narrow frequency band, so space and/or frequency diversity schemes can be applied to mitigate these effects. The effects of atmospheric stratification cause

8774-648: The publication by Johann Mattausch in the Austrian journal, Zeitschrift für Elektrotechnik. But his proposal was primitive and not suitable for practical use. The first experiments with radio repeater stations to relay radio signals were done in 1899 by Emile Guarini-Foresio. However the low frequency and medium frequency radio waves used during the first 40 years of radio proved to be able to travel long distances by ground wave and skywave propagation. In 1931, an Anglo-French consortium headed by Andre C. Clavier demonstrated an experimental microwave relay link across

8881-556: The radio path to bend downward in a typical situation so a major distance is possible as the earth equivalent curvature increases from 6,370 km (3,960 mi) to about 8,500 km (5,300 mi) (a 4/3 equivalent radius effect). Rare events of temperature, humidity and pressure profile versus height, may produce large deviations and distortion of the propagation and affect transmission quality. High-intensity rain and snow making rain fade must also be considered as an impairment factor, especially at frequencies above 10 GHz. All of

8988-408: The receiving antenna. This use of tightly-focused direct beams allows microwave transmitters in the same area to use the same frequencies, without interfering with each other as lower frequency radio waves would. This frequency reuse conserves scarce radio spectrum bandwidth. Another advantage is that the high frequency of microwaves gives the microwave band a very large information-carrying capacity;

9095-407: The same frequencies. The antennas must therefore be highly directional (high gain ), and are installed in elevated locations such as large radio towers in order to be able to avoid the obstructions closer to the ground and transmit across long distances. Typical types of antenna used in radio relay link installations are parabolic antennas , dielectric lens, and horn-reflector antennas , which have

9202-403: The signal field cause unwanted attenuation . High mountain peaks or ridges are often ideal positions for the antennas. In addition to the use of conventional repeaters with back-to-back radios transmitting on different frequencies, obstructions in microwave paths can also be dealt with by using Passive repeater or on-frequency repeaters. Obstacles, the curvature of the Earth, the geography of

9309-416: The television channels as well, allowing two 4 MHz signals to be carried in a single 10 MHz channel. They also added the ability to mix one television signal with addition telephone signals, which Bell referred to as "double decking". To lower the cost compared to the TD-2 system being deployed by AT&T in the US, Bell Canada used double decking where possible, simplified power supplies, and added

9416-399: The third largest number of telephones in the world despite its small population. More importantly, Canadians used their phones much more than any other nation, making an average of 411 calls per year. Existing long-distance lines would quickly be saturated, especially in the major markets. Studying the issue, Bell Canada decided to skip the use of coaxial cable connections being installed in

9523-417: The two groups build a single shared network. CNCP agreed to the proposal, but Bell rejected it, at which point CNCP dropped their interest in the project. The Cabinet stepped in and passed a law stating that no company would be allowed a monopoly, at which point CNCP began plans for their own network concentrating in the heavily populated areas east of Manitoba . With Bell as the only remaining contender for

9630-755: The war, the British Army introduced the Wireless Set No. 10, which used microwave relays to multiplex eight telephone channels over long distances. A link across the English Channel allowed General Bernard Montgomery to remain in continual contact with his group headquarters in London. In the post-war era, the development of microwave technology was rapid, which led to the construction of several transcontinental microwave relay systems in North America and Europe. In addition to carrying thousands of telephone calls at

9737-1038: The weather and other factors, and as a result, a high level of technical difficulty is involved in the creation of a reliable over horizon radio relay link. Troposcatter links are therefore only used in special circumstances where satellites and other long-distance communication channels cannot be relied on, such as in military communications. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km VLF 3 kHz/100 km 30 kHz/10 km LF 30 kHz/10 km 300 kHz/1 km MF 300 kHz/1 km 3 MHz/100 m HF 3 MHz/100 m 30 MHz/10 m VHF 30 MHz/10 m 300 MHz/1 m UHF 300 MHz/1 m 3 GHz/100 mm SHF 3 GHz/100 mm 30 GHz/10 mm EHF 30 GHz/10 mm 300 GHz/1 mm THF 300 GHz/1 mm 3 THz/0.1 mm AT%26T AT&T Inc. , an abbreviation for its predecessor's former name,

9844-551: The world, and to the key technology partners, suppliers, innovation and human resources needed as it continues to grow, domestically and internationally. AT&T Inc. previously relocated its corporate headquarters to San Antonio from St. Louis, Missouri, in 1992, when it was then named Southwestern Bell Corporation. The company's Telecom Operations group, which serves residential and regional business customers in 22 U.S. states, remains in San Antonio. Atlanta, Georgia, continues to be

9951-588: Was a bidder in the proposed sale of Warner Bros Interactive Entertainment, purchased the mobile gaming studio Playdemic from WBIE for US$ 1.4 billion in June 2021. In September 2021, Fox Corporation acquired TMZ from WarnerMedia in a deal worth about $ 50 million with TMZ being operated under the Fox Entertainment division. On December 21, 2021, AT&T announced that they had agreed to sell Xandr (and AppNexus ) to Microsoft for an undisclosed price. The deal

10058-413: Was among the first countries to implement telephone service using a microwave relay system, when in 1948 a link between Nova Scotia and Prince Edward Island opened with a capacity of 23 telephone lines. This was followed in 1952 by a radio system between Halifax and Saint John, New Brunswick , with 46 channels. Telephone usage grew explosively in the post-war era in Canada, and the country soon had

10165-445: Was built in 1979 by Telettra to transmit 300 telephone channels and one TV signal, in the 2 GHz frequency band. (Hop distance is the distance between two microwave stations). Previous considerations represent typical problems characterizing terrestrial radio links using microwaves for the so-called backbone networks: hop lengths of a few tens of kilometers (typically 10 to 60 km (6.2 to 37.3 mi)) were largely used until

10272-501: Was completed in June 2022. On April 8, 2022, the spinoff of WarnerMedia and its subsequent merger with Discovery, Inc. to form Warner Bros. Discovery was completed. As a result of this merger, HBO Max and other video services were dropped from AT&T's unlimited plan offering. AT&T was one of several clients of Snowflake Inc. that had data stolen in a 2024 breach. Phone and text logs from May 1, 2022 to October 31, 2022 of "nearly all" AT&T customers were exposed as part of

10379-403: Was continually expanded through the 1980s, adding higher frequencies on Anik B that reduced the ground antennas to about 2 metres (6 ft 7 in). These channels soon took over the entire television role from the Skyway. The network remained in use for both data and voice, undergoing numerous upgrades to keep it effective in the era of satellites. This came to an end with the introduction of

10486-413: Was expected at that time that the annual operating costs for microwave radio would be greater than for cable. There were two main reasons that a large capacity had to be introduced suddenly: Pent-up demand for long-distance telephone service, because of the hiatus during the war years, and the new medium of television, which needed more bandwidth than radio. The prototype was called TDX and was tested with

10593-421: Was microwaved over land to St. John's. The first television program played coast-to-coast was "Memo to Champlain", broadcast on Dominion Day. Among the many programs the network enabled was Hockey Night in Canada and a famous event held by CBC where people from across the country joined on television to sing Christmas carols live. It took just 20 milliseconds for a microwave signal to travel from one coast to

10700-479: Was one of the companies created by the breakup of AT&T Corp. The company soon started a series of acquisitions, including the 1987 acquisition of Metromedia mobile business and the acquisition of several cable companies in the early 1990s. In the latter half of the 1990s, the company acquired several other telecommunications companies, including two Baby Bells ( Pacific Telesis Group and Ameritech Corporation ), while selling its cable business. During this time,

10807-590: Was proposed, but ultimately abandoned due to COVID-19 pandemic -related growth in the video gaming industry, as well as a positive reception to upcoming DC Comics , Lego Star Wars , and Harry Potter titles from fans and critics. Crunchyroll was sold to Sony 's Funimation for US$ 1.175 billion in December 2020, with the acquisition closing in August 2021. On February 25, 2021, AT&T announced that it would spin-off DirecTV, U-Verse TV, and DirecTV Stream into

10914-428: Was reported that AT&T planned to launch a new cable TV-like service for delivery over-the-top over its own or a competitor's broadband network sometime the following year. On March 7, 2018, the company prepared to sell a minority stake of DirecTV Latin America through an IPO , creating a new holding company for those assets named Vrio Corp. On April 18, just a day before the public debut of Vrio, AT&T canceled

11021-407: Was similar to the TD-2 system but operated at higher frequencies between 5,974 MHz and 6,404 MHz, using the same 118 MHz channel spacing. Rogers Communications bought 40% of the network in 1984 and increasingly took it over after that point. The railways eventually sold their stake in the system, which provided the early backbone for Roger's cellular telephone network. As traffic on

11128-406: Was the American Telephone and Telegraph Company (AT&T), established in 1885. On December 30, 1899, AT&T acquired the assets of its parent American Bell Telephone, becoming the new parent company. AT&T established a network of local telephone subsidiaries in the United States. AT&T and its subsidiaries held a phone service monopoly , authorized in 1913 by government authorities with

11235-418: Was the fourteenth-largest donor to United States federal political campaigns and committees from 1989 to 2019, having contributed more than US$ 84.1 million , 42% of which went to Republicans and 58% of which went to Democrats . In 2005, AT&T was among 53 entities that contributed the maximum of $ 250,000 to the second inauguration of President George W. Bush . Bill Leahy, representing AT&T, sits on

11342-563: Was the longest microwave relay in the world. It was further extended to Newfoundland in 1959. To get it to Newfoundland, it was fed from Sydney, to a repeater in Cape North that was 427 metres above sea-level. That allowed it cross the 127 kilometres across the Cabot Strait to a repeater station perched 198 metres above sea-level in Red Rocks, Newfoundland and Labrador . From there, the signal

11449-476: Was then multiplexed with other customer streams using time division multiplexing , and then injected into the Skyway network at the nearest site. It was expected this would reduce the cost of transmission by about one-half compared to existing systems; using the network as a traditional analog system using modems required a conventional telephone call to be established between the sites, which might take 15 to 20 seconds, which might be more time than required to send

#691308