AM broadcasting is a radio broadcasting technology, which employs amplitude modulation transmissions. It was the first method developed for making audio radio transmissions, is still used worldwide for medium wave transmissions, but on the longwave and shortwave radio bands; the earliest experimental AM transmissions began in the early 1900s. However, widespread AM broadcasting was not established until the 1920s, following the development of vacuum tube receivers and transmitters. AM radio remained the dominant method of broadcasting for the next 30 years, a period called the "Golden Age of Radio", until television broadcasting became widespread in the 1950s and received most of the programming carried by radio. Subsequently, AM radio's audiences have greatly shrunk due to competition from FM radio, Digital Audio Broadcasting, satellite radio, HD radio and Internet streaming. AM transmissions are much more susceptible than FM or digital signals are to interference, have lower audio fidelity.
Thus, AM broadcasters tend to specialise in spoken-word formats, such as talk radio, all news and sports, leaving the broadcasting of music to FM and digital stations. The idea of broadcasting — the unrestricted transmission of signals to a widespread audience — dates back to the founding period of radio development though the earliest radio transmissions known as "Hertzian radiation" and "wireless telegraphy", used spark-gap transmitters that could only transmit the dots-and-dashes of Morse code. In October 1898 a London publication, The Electrician, noted that "there are rare cases where, as Dr. Lodge once expressed it, it might be advantageous to'shout' the message, spreading it broadcast to receivers in all directions". However, it was recognized that this would involve significant financial issues, as that same year The Electrician commented "did not Prof. Lodge forget that no one wants to pay for shouting to the world on a system by which it would be impossible to prevent non-subscribers from benefiting gratuitously?"On January 1, 1902, Nathan Stubblefield gave a short-range "wireless telephone" demonstration, that included broadcasting speech and music to seven locations throughout Murray, Kentucky.
However, this was transmitted using induction rather than radio signals, although Stubblefield predicted that his system would be perfected so that "it will be possible to communicate with hundreds of homes at the same time", "a single message can be sent from a central station to all parts of the United States", he was unable to overcome the inherent distance limitations of this technology. The earliest public radiotelegraph broadcasts were provided as government services, beginning with daily time signals inaugurated on January 1, 1905, by a number of U. S. Navy stations. In Europe, signals transmitted from a station located on the Eiffel tower were received throughout much of Europe. In both the United States and France this led to a small market of receiver lines designed geared for jewelers who needed accurate time to set their clocks, including the Ondophone in France, the De Forest RS-100 Jewelers Time Receiver in the United States The ability to pick up time signal broadcasts, in addition to Morse code weather reports and news summaries attracted the interest of amateur radio enthusiasts.
It was recognized that, much like the telegraph had preceded the invention of the telephone, the ability to make audio radio transmissions would be a significant technical advance. Despite this knowledge, it still took two decades to perfect the technology needed to make quality audio transmissions. In addition, the telephone had been used for distributing entertainment, outside of a few "telephone newspaper" systems, most of which were established in Europe. With this in mind, most early radiotelephone development envisioned that the device would be more profitably developed as a "wireless telephone" for personal communication, or for providing links where regular telephone lines could not be run, rather than for the uncertain finances of broadcasting; the person credited as the primary early developer of AM technology is Canadian-born inventor Reginald Fessenden. The original spark-gap radio transmitters were impractical for transmitting audio, since they produced discontinuous pulses known as "damped waves".
Fessenden realized that what was needed was a new type of radio transmitter that produced steady "undamped" signals, which could be "modulated" to reflect the sounds being transmitted. Fessenden's basic approach was disclosed in U. S. Patent 706,737, which he applied for on May 29, 1901, was issued the next year, it called for the use of a high-speed alternator that generated "pure sine waves" and produced "a continuous train of radiant waves of uniform strength", or, in modern terminology, a continuous-wave transmitter. Fessenden began his research on audio transmissions while doing developmental work for the United States Weather Service on Cobb Island, Maryland; because he did not yet have a continuous-wave transmitter he worked with an experimental "high-frequency spark" transmitter, taking advantage of the fact that the higher the spark rate, the closer a spark-gap transmission comes to producing continuous waves. He reported that, in the fall of 1900, he transmitted speech over a distance of about 1.6 kilometers, which appears to have been the first successful audio transmission using radio signals.
However, at this time the sound was far too distorted to be commercially practical. For a time he continued working with more sophist
Intelsat Corporation—formerly INTEL-SAT, INTELSAT, Intelsat—is a communications satellite services provider. Formed as International Telecommunications Satellite Organization, it was—from 1964 to 2001—an intergovernmental consortium owning and managing a constellation of communications satellites providing international broadcast services; as of March 2011, Intelsat operates a fleet of 52 communications satellites, one of the world's largest fleet of commercial satellites. They claim to serve around 1,500 customers and employ a staff of 1,100 people. John F. Kennedy instigated the creation of INTELSAT with his speech to the United Nations on the 25th of September 1961. Less than a year John F. Kennedy signed the Communications Satellite Act of 1962. INTELSAT was formed as International Telecommunications Satellite Organization and operated from 1964 to 2001 as an intergovernmental consortium owning and managing a constellation of communications satellites providing international broadcast services.
In 2001, the international satellite market was commercialized, the US predominant role in INTELSAT was privatized after 2001 as Intelsat was formed up as a private Luxembourg corporation. The International Governmental Organization began on 20 August 1964, with 7 participating countries; the 1964 agreement was an interim arrangement on a path to a more permanent agreement. The permanent international organization was established in 1973, following inter-nation negotiations from 1969 to 1971; the most difficult issue to "resolve concerned the shift from management of the system by a national entity to management by the international organization itself."On 6 April 1965, INTELSAT's first satellite, the Intelsat I, was placed in geostationary orbit above the Atlantic Ocean by a Delta D rocket. In 1973, the name was changed and there were 81 signatories. INTELSAT was "governed by two international agreements: The Agreement setting forth the basic provisions and principles and structure of the organization, signed by the governments through their foreign ministries, an Operating Agreement setting forth more detailed financial and technical provisions and signed by the governments or their designated telecommunications entities."—in most cases the latter are the ministries of communications of the party countries, but in the case of the United States, was the Communications Satellite Corporation, a private corporation established by federal legislation to represent the US in international governance for the global communication satellite system.
INTELSAT at that time directly owned and managed a global communications satellite system, structurally consisted of three parts: the Assembly of Parties—meeting every two years and concerned with aspects "primarily of interest to the Parties as sovereign States."—with each country having one vote. The Meeting of Signatories—meeting annually and composed of all the signatories to the Operating Agreement—primarily working on financial and program matters, with each countries' signatory having one vote. A Board of Governors, meeting at least four times each year, making decisions on design, establishment and maintenance of the in-space assets, appointed by signatories, but weighted to each signatories "investment share" in the space assets; the 1973 Agreement called for a seven-year transition from national to international management, but continued until 1976 to carve out "technical and operational management of the system the Communications Satellite Corporation served as the Manager of the global system under the interim arrangements in force from 1964 to 1973."
Phases of the transition resulted in full international governance by 1980. Financial contribution to the organization, it's so-called "investment share," was proportional to each member's use of the system, determined annually. Intelsat provides service to over 600 Earth stations in more than 149 countries and dependencies. By 2001, INTELSAT had over 100 members, it was this year that INTELSAT privatized and changed its name to Intelsat. Since its inception, Intelsat has used several versions of its dedicated Intelsat satellites. Intelsat completes each block of spacecraft independently, leading to a variety of contractors over the years. Intelsat’s largest spacecraft supplier is Space Systems/Loral, having built 31 spacecraft, or nearly half of the fleet; the network in its early years was not as robust. A failure of the Atlantic satellite in the spring of 1969 threatened to stop the Apollo 11 mission. During the Apollo 11 moonwalk, the moon was over the Pacific Ocean, so other antennas were used, as well as INTELSAT III, in geostationary orbit over the Pacific.
By the 1990s, building and launching satellites was no longer a government domain and as country-specific telecommunications systems were privatized, several private satellite operators arose to meet the growing demand. In the U. S. satellite operators such as PanAmSat, Orion Communications, Columbia Communications, Globalstar, TRW and others formed under the umbrella of the Alliance for Competitive International Satellite Services to press for an end to the IGOs and the monopoly position of COMSAT the US signatory to Intelsat and Inmarsat. In March 2001, the US Congress passed the Open Market Reorganisation for the B
Shortwave radio is radio transmission using shortwave radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band, extends from 1.7–30 MHz. Radio waves in the shortwave band can be reflected or refracted from a layer of electrically charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances, beyond the horizon; this is called skywave or "skip" propagation. Thus shortwave radio can be used for long distance communication, in contrast to radio waves of higher frequency which travel in straight lines and are limited by the visual horizon, about 64 km. Shortwave radio is used for broadcasting of voice and music to shortwave listeners over large areas, it is used for military over-the-horizon radar, diplomatic communication, two-way international communication by amateur radio enthusiasts for hobby and emergency purposes, as well as for long distance aviation and marine communications.
The widest popular definition of the shortwave frequency interval is the ITU Region 1 definition, is the span 1.6–30 MHz, just above the medium wave band, which ends at 1.6 MHz. There are other definitions of the shortwave frequency interval: 1.71 to 30 MHz in ITU Region 2 1.8 to 30 MHz 2.3 to 30 MHz 2.3 to 26.1 MHz In Germany and Austria the ITU Region 1 shortwave radio frequency interval can be subdivided in: de:Grenzwelle: 1.605–3.8 MHz In Germany these shortwave radio frequency intervals have been seen used: the above other definitions The name "shortwave" originated during the early days of radio in the early 20th century, when the radio spectrum was considered divided into long wave, medium wave and short wave bands based on the wavelength of the radio waves. Shortwave radio received its name because the wavelengths in this band are shorter than 200 m which marked the original upper limit of the medium frequency band first used for radio communications; the broadcast medium wave band now extends above the 200 m/1,500 kHz limit, the amateur radio 1.8 MHz – 2.0 MHz band is the lowest-frequency band considered to be'shortwave'.
Early long distance radio telegraphy used long waves, below 300 kilohertz. The drawbacks to this system included a limited spectrum available for long distance communication, the expensive transmitters and gigantic antennas that were required, it was difficult to beam the radio wave directionally with long wave, resulting in a major loss of power over long distances. Prior to the 1920s, the shortwave frequencies above 1.5 MHz were regarded as useless for long distance communication and were designated in many countries for amateur use. Guglielmo Marconi, pioneer of radio, commissioned his assistant Charles Samuel Franklin to carry out a large scale study into the transmission characteristics of short wavelength waves and to determine their suitability for long distance transmissions. Franklin rigged up a large antenna at Poldhu Wireless Station, running on 25 kW of power. In June and July 1923, wireless transmissions were completed during nights on 97 meters from Poldhu to Marconi's yacht Elettra in the Cape Verde Islands.
In September 1924, Marconi transmitted daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut. Franklin went on to refine the directional transmission, by inventing the curtain array aerial system. In July 1924, Marconi entered into contracts with the British General Post Office to install high speed shortwave telegraphy circuits from London to Australia, South Africa and Canada as the main element of the Imperial Wireless Chain; the UK-to-Canada shortwave "Beam Wireless Service" went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa and India went into service in 1927. Shortwave communications began to grow in the 1920s, similar to the internet in the late 20th century. By 1928, more than half of long distance communications had moved from transoceanic cables and longwave wireless services to shortwave and the overall volume of transoceanic shortwave communications had vastly increased. Shortwave stations had cost and efficiency advantages over massive longwave wireless installations, however some commercial longwave communications stations remained in use until the 1960s.
Long distance radio circuits reduced the load on the existing transoceanic telegraph cables and hence the need for new cables, although the cables maintained their advantages of high security and a much more reliable and better quality signal than shortwave. The cable companies began to lose large sums of money in 1927, a serious financial crisis threatened the viability of cable companies that were vital to strategic British interests; the British government convened the Imperial Wireless and Cable Conference in 1928 "to examine the situation that had arisen as a result of the competition of Beam Wireless with the Cable Services". It recommended and received Government approval for all overseas cable and wireless resources of the Empire to be merged into one system controlled by a newly formed company in 1929, Imperial and International Communications Ltd; the name of the company was changed to Cable and Wireless Ltd. in 1934. Long-distance cables had a
Internet service provider
An Internet service provider is an organization that provides services for accessing, using, or participating in the Internet. Internet service providers may be organized in various forms, such as commercial, community-owned, non-profit, or otherwise owned. Internet services provided by ISPs include Internet access, Internet transit, domain name registration, web hosting, Usenet service, colocation; the Internet was developed as a network between government research laboratories and participating departments of universities. Other companies and organizations joined by direct connection to the backbone, or by arrangements through other connected companies, sometime using dialup tools such as UUCP. By the late 1980s, a process was set in place towards commercial use of the Internet; the remaining restrictions were removed by 1991, shortly after the introduction of the World Wide Web. During the 1980s, online service providers such as CompuServe and America On Line began to offer limited capabilities to access the Internet, such as e-mail interchange, but full access to the Internet was not available to the general public.
In 1989, the first Internet service providers, companies offering the public direct access to the Internet for a monthly fee, were established in Australia and the United States. In Brookline, The World became the first commercial ISP in the US, its first customer was served in November 1989. These companies offered dial-up connections, using the public telephone network to provide last-mile connections to their customers; the barriers to entry for dial-up ISPs were low and many providers emerged. However, cable television companies and the telephone carriers had wired connections to their customers and could offer Internet connections at much higher speeds than dial-up using broadband technology such as cable modems and digital subscriber line; as a result, these companies became the dominant ISPs in their service areas, what was once a competitive ISP market became a monopoly or duopoly in countries with a commercial telecommunications market, such as the United States. On 23 April 2014, the U.
S. Federal Communications Commission was reported to be considering a new rule that will permit ISPs to offer content providers a faster track to send content, thus reversing their earlier net neutrality position. A possible solution to net neutrality concerns may be municipal broadband, according to Professor Susan Crawford, a legal and technology expert at Harvard Law School. On 15 May 2014, the FCC decided to consider two options regarding Internet services: first, permit fast and slow broadband lanes, thereby compromising net neutrality. On 10 November 2014, President Barack Obama recommended that the FCC reclassify broadband Internet service as a telecommunications service in order to preserve net neutrality. On 16 January 2015, Republicans presented legislation, in the form of a U. S. Congress H. R. discussion draft bill, that makes concessions to net neutrality but prohibits the FCC from accomplishing the goal or enacting any further regulation affecting Internet service providers. On 31 January 2015, AP News reported that the FCC will present the notion of applying Title II of the Communications Act of 1934 to the Internet in a vote expected on 26 February 2015.
Adoption of this notion would reclassify Internet service from one of information to one of the telecommunications and, according to Tom Wheeler, chairman of the FCC, ensure net neutrality. The FCC is expected to enforce net neutrality in its vote, according to The New York Times. On 26 February 2015, the FCC ruled in favor of net neutrality by adopting Title II of the Communications Act of 1934 and Section 706 in the Telecommunications Act of 1996 to the Internet; the FCC Chairman, Tom Wheeler, commented, "This is no more a plan to regulate the Internet than the First Amendment is a plan to regulate free speech. They both stand for the same concept." On 12 March 2015, the FCC released the specific details of the net neutrality rules. On 13 April 2015, the FCC published the final rule on its new "Net Neutrality" regulations; these rules went into effect on 12 June 2015. Upon becoming FCC chairman in April 2017, Ajit Pai proposed an end to net neutrality, awaiting votes from the commission. On 21 November 2017, Pai announced that a vote will be held by FCC members on 14 December on whether to repeal the policy.
On 11 June 2018, the repeal of the FCC's network neutrality rules took effect. Access provider ISPs provide Internet access, employing a range of technologies to connect users to their network. Available technologies have ranged from computer modems with acoustic couplers to telephone lines, to television cable, Wi-Fi, fiber optics. For users and small businesses, traditional options include copper wires to provide dial-up, DSL asymmetric digital subscriber line, cable modem or Integrated Services Digital Network. Using fiber-optics to end users is called Fiber To The Home or similar names. For customers with more demanding requirements can use higher-speed DSL, metropolitan Ethernet, gigabit Ethernet, Frame Relay, ISDN Primary Rate Interface, ATM and synchronous optical networking. Wireless access is another option, including satellite Internet access. A mailbox provider is an organization that provides services for hosting electronic mail domains with access to storage for mail boxes
Telecommunications in Ethiopia
Telecommunications in Ethiopia is a monopoly in the control of Ethio Telecom the Ethiopian Telecommunications Corporation. As of 2012, 20.524 million cellular phones and 797,500 main line phones were in use. The telephone system in Ethiopia consists of open wire and microwave radio relay systems adequate for government use. Domestic systems are open wire. International systems are open wire to Sudan; the Ethiopian dial plan changed on 17 September 2005. City codes changed from two digits to three. Phone numbers changed from six digits to seven. In 2007, there were 89 internet hosts. There were 447,300 internet users in 2009. In 2010, just 0.75 percent of the population were using the Internet, one of the lowest rates in the world. Ethiopia's country code is.et. The first telegraph line in Ethiopia was constructed in the years 1897 - 1899 between the cities of Harar and the capital Addis Ababa; this was extended in 1904 by a line that ran from Addis Ababa through Tigray into Eritrea and to Massawa. The first telephones were brought by Ras Makonnen from Italy in 1890, connected between the Palace and the Imperial treasury.
The Emperor Menelik II responded to their protests with disdain, used the telephone to give orders to his provincial governors. Emperor Haile Selassie had begun the process of introducing radio transmitters to the country for civilian and military use in the years before the Italian invasion. According to the ETC, the average rural inhabitant of Ethiopia has to walk 30 kilometers to the nearest phone; the ETC announced 7 September 2006 a program to improve national coverage, reduce the average distance to 5 kilometers. Since 2008 CDMA2000 and WCDMA is available in certain areas. Since 26 September 2017, it is not possible to buy and use Ethio Tel SIM cards in mobile devices that haven’t been purchased in Ethiopia or registered with the authorities. Local advice suggests travellers should register their phone in the customs arrival hall at Bole airport on arrival if they intend to use a local SIM card. For travellers, local prepaid SIMs are available at Ethio Telecom Kiosks and hotels. Satellite phones may require letter of permission from the ETC prior to bringing such phones through customs.
Use of voice over IP services such as Skype and Google Talk was prohibited by telecommunications legislation in 2002. Personal use of these services was legalised by the Proclamation on Telecom Fraud Offences of 2012. Since the changes and upgrade of equipment in the mid-2000 the telecommunication network is out of work or overloaded, callers using both the landlines and mobile network are unable to connect, the situation is made worse by inclement weather; the ETC has not addressed this issue publicly nor admitted that the coverage and service is below par. Ethiopian telecom has launched the Fourth Generation Long-Term Evolution service on March 21, 2015 in line with the help of the Chinese company HUAWEI. Ethio-Telecom Corporate Compunction Officer, Abdurahim Mohammed, stated that the rural telecom access within 5 km radius service has reached 96 per cent; as part of the efforts to expand its service and improve network quality, Ethio Telecom had built 725 stations in Addis Ababa alone during the past 20 years, he said.
Damages on fiber optic cables and power interruptions are among the challenges the service provider faced in its expansion and network quality improvement efforts, he said. Internet in Ethiopia Ethiopian Telecommunication Agency Ethiopian Telecommunications Corporation Terrestrial fibre optic cable projects in Ethiopia ETV Media in Ethiopia Communications in Ethiopia PanAfriL10n page on Ethiopia "The Internet in Ethiopia" "Internet in Ethiopia Revisited – A Mixed Bag of Progress and Opportunities on-Hold" "Ethiopia's digital dream"
Telecommunications in Angola
Telecommunications in Angola include telephone, radio and the Internet. The government controls all broadcast media with a nationwide reach. In 2001, toward the end of Angolan Civil War, the government began adopting regulations to liberalize the telecom industry; this enabled private investments to revitalize the country’s telecommunications infrastructure, damaged by the decades-long conflict. By 2012, Angola had one of the largest mobile telecom markets in sub-Saharan Africa and Internet access was growing steadily; the Ministry of Post and Telecommunications oversees the telecommunications sector, regulated by the Angolan National Institute of Telecommunication. 29 satellite earth stations. SAT-3/WASC fiber optic submarine cable provides connectivity to Europe and Asia. AngoSat 1, Angola's first communication satellite, built by RSC Enegria with a credit from Rosoboronexport, is scheduled to launch in 2017. Angola Telecom is one of twelve companies participating in the West Africa Cable System consortium, a submarine communications cable running along the west coast of Africa and on to Portugal and the United Kingdom.
The landing station for the older Sat3 cable, located at Cacuaco in Luanda, is operated by Angola Telecom. Angola Cables is an operator of fiber optic telecommunication systems formed in 2009 by the major Angolan telecommunication companies, Angola Telecom, Unitel, MSTelcom and Mundo Startel. On 23 March 2012 Angola Cables signed an agreement to participate in the construction of the South Atlantic Cable System of about 6000 km length linking Fortaleza in Brazil with the Angolan capital Luanda; this cable is planned to be operational from the 2014 world football championship in Brazil. ADONES consists of 1,800 kilometers of fiber-optic submarine cable linking eight Angolan coastal cities. About 70 percent of Angolans live close to the sea. Other planned fibre optic cables to Angola include SAex and ACE. 303,200 fixed lines, 116th in the world, two lines per 100 persons. 13 million mobile cellular lines, 65 lines per 100 persons.) International country code: 244. Angola Telecom, the state-owned telecom, held a monopoly for fixed-line telephone service until 2005.
Demand outstripped capacity, prices were high, services poor. Telecom Namibia, through an Angolan company, became the first private licensed operator in Angola's fixed-line telephone network. By 2010, the number of fixed-line providers had expanded to five. A owned, mobile-cellular service provider began operations in 2001. HF radiotelephone is used extensively for military links. 21 AM, 6 FM, 7 shortwave radio broadcast stations 630,000 radios The state-owned Radio Nacional de Angola broadcasts on 5 stations. A half dozen private radio stations broadcast locally. 6 television broadcast stations 150,000 televisions The state-owned Televisão Pública de Angola provides terrestrial TV service on two channels and a third TPA channel is available via cable and satellite. TV subscription services are available. Internet hosts: 20,703 hosts, 116th in the world. Internet users: 3,058,195 users, 78th in the world. Fixed broadband: 27,987 subscriptions, 124th in the world. Mobile broadband: 5.000.000 subscriptions.
2015. Top level domain name:.ao. First introduced in 1996, the Internet reached a penetration rate of 16.9 percent in 2012, up from just over 3 percent in 2007, according to the International Telecommunications Union. Fixed-line broadband subscriptions, remain low with a penetration rate of only 0.2 percent in 2012, are concentrated in the capital city, due to the country’s high poverty rate and poor infrastructure in rural areas. Mobile Internet access is higher at 1.5% and access to mobile phones is much higher with a penetration rate of 49% in 2012. In June 2012, Unitel launched a project in partnership with the education ministry and Huawei to provide free Internet access for secondary school students in both public and private schools across the country’s 18 provinces. Known as “E-Net,” the project aims to benefit over 18,000 students with computers supplied by Huawei and Internet access provided by Unitel. Citizens have taken to the Internet as a platform for political debate, to express discontent with the country’s current state of affairs, to launch digital activism initiatives.
Similar to many other African countries, Angolan youth have embraced social media tools and used them to fuel protest movements across the country. The positive impact of digital media tools in Angola was noticeable during the August 2012 parliamentary elections when the Internet was used in innovative ways to advance electoral transparency. For example, citizens were able to report electoral irregularities in real time, while the National Electoral Commission used the Internet and iPads to scan voter registration cards. Internet access in Angola is provided by private ISP's. Telecommunication companies: Angola Telecom, the state-owned telecommunications provider Itelnet MS Telcom, Sonangol owned provider, main focus on oil and gas sector Startel Internet Service Providers: ACS CmcAngola covers majority of luanda and other areas with VSAT technologies ITA - Internet Technologies Angola owned with a focus on corporate services Multitel, corporate focused ISP, subsidiary of Angola Telecom MVcomm NetOne, residential WiMAX services TSOLNETWORKS - Corporate Internet Se
The Indian Ocean is the third largest of the world's oceanic divisions, covering 70,560,000 km2. It is bounded by Asia on the north, on the west by Africa, on the east by Australia, on the south by the Southern Ocean or, depending on definition, by Antarctica; the Indian Ocean is named after India. Called the Sindhu Mahasagara or the great sea of the Sindhu by the Ancient Indians, this ocean has been variously called Hindu Ocean, Indic Ocean, etc. in various languages. The Indian Ocean was known earlier as the Eastern Ocean; the term was still in use during the mid-18th century. The borders of the Indian Ocean, as delineated by the International Hydrographic Organization in 1953 included the Southern Ocean but not the marginal seas along the northern rim, but in 2000 the IHO delimited the Southern Ocean separately, which removed waters south of 60°S from the Indian Ocean, but included the northern marginal seas. Meridionally, the Indian Ocean is delimited from the Atlantic Ocean by the 20° east meridian, running south from Cape Agulhas, from the Pacific Ocean by the meridian of 146°49'E, running south from the southernmost point of Tasmania.
The northernmost extent of the Indian Ocean is 30° north in the Persian Gulf. The Indian Ocean covers 70,560,000 km2, including the Red Sea and the Persian Gulf but excluding the Southern Ocean, or 19.5% of the world's oceans. The ocean's continental shelves are narrow. An exception is found off Australia's western coast; the average depth of the ocean is 3,890 m. Its deepest point is Sunda Trench at a depth of 7,450 m. North of 50° south latitude, 86% of the main basin is covered by pelagic sediments, of which more than half is globigerina ooze; the remaining 14% is layered with terrigenous sediments. Glacial outwash dominates the extreme southern latitudes; the major choke points include Bab el Mandeb, Strait of Hormuz, the Lombok Strait, the Strait of Malacca and the Palk Strait. Seas include the Gulf of Aden, Andaman Sea, Arabian Sea, Bay of Bengal, Great Australian Bight, Laccadive Sea, Gulf of Mannar, Mozambique Channel, Gulf of Oman, Persian Gulf, Red Sea and other tributary water bodies.
The Indian Ocean is artificially connected to the Mediterranean Sea through the Suez Canal, accessible via the Red Sea. All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere, the 90th meridian east, passes through the Ninety East Ridge. Marginal seas, gulfs and straits of the Indian Ocean include: Several features make the Indian Ocean unique, it constitutes the core of the large-scale Tropical Warm Pool which, when interacting with the atmosphere, affects the climate both regionally and globally. Asia prevents the ventilation of the Indian Ocean thermocline; that continent drives the Indian Ocean monsoon, the strongest on Earth, which causes large-scale seasonal variations in ocean currents, including the reversal of the Somali Current and Indian Monsoon Current. Because of the Indian Ocean Walker circulation there is no continuous equatorial easterlies. Upwelling occurs near the Horn of Africa and the Arabian Peninsula in the Northern Hemisphere and north of the trade winds in the Southern Hemisphere.
The Indonesian Throughflow is a unique Equatorial connection to the Pacific. The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April. In the Arabian Sea the violent Monsoon brings rain to the Indian subcontinent. In the southern hemisphere, the winds are milder, but summer storms near Mauritius can be severe; when the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the Bay of Bengal. The Indian Ocean is the warmest ocean in the world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, at about 0.7–1.2 °C during 1901–2012. Indian Ocean warming is the largest among the tropical oceans, about 3 times faster than the warming observed in the Pacific. Research indicates that human induced greenhouse warming, changes in the frequency and magnitude of El Niño events are a trigger to this strong warming in the Indian Ocean. South of the Equator the Indian Ocean is gaining heat from June to October, during the austral winter, while it is losing heat from November to March, during the austral summer.
Among the few large rivers flowing into the Indian Ocean are the Zambezi and Jubba in Africa. The ocean's currents are controlled by the monsoon. Two large gyres, one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise, constitute the dominant flow pattern. During the winter monsoon, circulation is reversed north of 30°S and winds are weakened during winter and the transitional periods between the monsoons. Deep water circulation is controlled by inflows from the Atlantic Ocean, the Red Sea, Antarctic currents. North of 20 ° south latitude the minimum surface temperature is 22 °C. Southward of 40° south latitude, temperatures