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98-451: K u band is primarily used for satellite communications , most notably the downlink used by direct broadcast satellites to broadcast satellite television , and for specific applications such as NASA 's Tracking Data Relay Satellite used for International Space Station (ISS) communications and SpaceX Starlink satellites. K u band satellites are also used for backhauls and particularly for satellite from remote locations back to

196-788: A band transponders. NSS 6 , launched in December 2002 and positioned at 95° East, contains only K u -band transponders with a footprint on Indonesia ( Sumatra , Java , Borneo , Celebes , Bali , Nusa Tenggara , Moluccas ). NSS 6 is intended to be replaced by SES-12 at the same location, which launched in June 2018 and carries 54 K u -band transponders. The IPSTAR 1 satellite, launched in 2004 also uses K u band footprints. Other satellites that provides K u band covers Indonesia are MEASAT-3b , JCSAT-4B , AsiaSat 5 , ST-2 , Chinasat 11, Koreasat 8/ABS-2 , SES-8 , Telkom-3S , and Nusantara Satu . Other ITU allocations have been made within

294-771: A television network's studio for editing and broadcasting . The band is split by the International Telecommunication Union (ITU) into multiple segments that vary by geographical region. NBC was the first television network to uplink a majority of its affiliate feeds via K u band in 1983. Some frequencies in this radio band are employed in radar guns used by law enforcement to detect vehicles speeding, especially in Europe. Segments in most of North and South America are represented by ITU Region 2 from 11.7 to 12.2 GHz ( Local Oscillator Frequency (LOF) 10.75 to 11.25 GHz), allocated to

392-565: A wetland of international importance under the Ramsar Convention . Sumatra has lost almost 50% of its tropical rainforest since 1980. Many species are now critically endangered , such as the Sumatran ground cuckoo , the Sumatran tiger , the Sumatran elephant , the Sumatran rhinoceros , and the Sumatran orangutan . Deforestation on the island has also resulted in serious seasonal smoke haze over neighbouring countries, such as

490-491: A 9.2 earthquake shook Bengkulu and Western Sumatra. Both events caused large tsunamis . Earthquakes are very common throughout the coastal area of the west and center of the island, and tsunamis are common due to the high seismicity in the area. By population, Medan is the largest city in Sumatra. Medan is also the most visited and developed city in Sumatra. Sumatra supports a wide range of vegetation types that are home to

588-455: A data network aiming to provide a „Lunar Internet for cis-lunar spacecraft and Installations. The Moonlight Initiative is an equivalent ESA project that is stated to be compatible and providing navigational services for the lunar surface. Both programmes are satellite constellstions of several satellites in various orbits around the Moon. Other orbits are also planned to be used. Positions in

686-848: A dish of a given size. Position feedback accuracies are higher and the antenna may require a closed loop control system to maintain position under wind loading of the dish surface. 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 Satellite communication A communications satellite

784-532: A heavy rain area usually gives poor results. This problem can be solved by using an appropriate link budget when designing the wireless communication link. Higher power can overcome the loss to rain fade . Measurements of rain attenuation in Indonesia have been done for satellite communication links in Padang, Cibinong, Surabaya and Bandung. The DAH Model for rain attenuation prediction is valid for Indonesia, as

882-588: A higher powered signal from the satellite to compensate. Therefore, the K u band satellites typically require considerably more power to transmit than the C-band satellites. Another weather-caused degradation called "snow fade" is not specific to the K u band. It is due to snow or ice accumulation on a dish significantly altering its focal point. The satellite operator's Earth station antenna requires more accurate position control when operating at K u band due to its much narrower beam focus compared to C band for

980-518: A medium Earth orbit satellite is about 16,000 kilometres (10,000 mi) above Earth. In various patterns, these satellites make the trip around Earth in anywhere from 2 to 8 hours. To an observer on Earth, a satellite in a gestationary orbit appears motionless, in a fixed position in the sky. This is because it revolves around the Earth at Earth's own angular velocity (one revolution per sidereal day , in an equatorial orbit ). A geostationary orbit

1078-538: A more precise match for the capabilities of geosynchronous comsats. Two satellite types are used for North American television and radio: Direct broadcast satellite (DBS), and Fixed Service Satellite (FSS). The definitions of FSS and DBS satellites outside of North America, especially in Europe, are a bit more ambiguous. Most satellites used for direct-to-home television in Europe have the same high power output as DBS-class satellites in North America, but use

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1176-687: A number of satellites for various purposes; for example, METSAT for meteorological satellite, EUMETSAT for the European branch of the program, and METOP for meteorological operations. These orbits are Sun synchronous, meaning that they cross the equator at the same local time each day. For example, the satellites in the NPOESS (civilian) orbit will cross the equator, going from south to north, at times 1:30 P.M., 5:30 P.M., and 9:30 P.M. There are plans and initiatives to bring dedicated communications satellite beyond geostationary orbits. NASA proposed LunaNet as

1274-621: A period (time to revolve around the Earth) of about 90 minutes. Because of their low altitude, these satellites are only visible from within a radius of roughly 1,000 kilometres (620 mi) from the sub-satellite point. In addition, satellites in low Earth orbit change their position relative to the ground position quickly. So even for local applications, many satellites are needed if the mission requires uninterrupted connectivity. Low-Earth-orbiting satellites are less expensive to launch into orbit than geostationary satellites and, due to proximity to

1372-545: A radio signal to a telephone system. In this example, almost any type of satellite can be used. Satellite phones connect directly to a constellation of either geostationary or low-Earth-orbit satellites. Calls are then forwarded to a satellite teleport connected to the Public Switched Telephone Network . As television became the main market, its demand for simultaneous delivery of relatively few signals of large bandwidth to many receivers being

1470-528: A rich variety of species, including 17 endemic genera of plants. Unique species include the Sumatran pine which dominates the Sumatran tropical pine forests of the higher mountainsides in the north of the island and rainforest plants such as Rafflesia arnoldii (the world's largest individual flower), and the titan arum (the world's largest unbranched inflorescence ). The island is home to 201 mammal species and 580 bird species. There are nine endemic mammal species on mainland Sumatra and 14 more endemic to

1568-675: A stiff economic decline as the heritage of the Srivijaya empire was superseded by the economic policy of the Singhasari and Majapahit . The Palembang sultanate experienced a terminal decline in the early 19th century. With the coming of the Dutch Empire , the many Sumatran princely states gradually fell under their control. Aceh posed major obstacles, as the Dutch were involved in the long and costly Aceh War (1873–1903). During

1666-523: A tactical necessity, and the ultimate goal of this project was the creation of the longest communications circuit in human history, with the Moon, Earth's natural satellite, acting as a passive relay. After achieving the first transoceanic communication between Washington, D.C. , and Hawaii on 23 January 1956, this system was publicly inaugurated and put into formal production in January 1960. The first satellite purpose-built to actively relay communications

1764-495: Is also an area in the archipelago that received the spread of Islam first compared to other islands or other areas. The island of Sumatra became the first area to receive the spread of Islam because of the position of the island of Sumatra which is close to the Malacca strait. The initial process of Islamization related to trade and also the formation of the kingdom. Islam entered Sumatra through pious Arabs and Tamil traders in

1862-447: Is also less vulnerable to rain fade than the K a band frequency spectrum. There are, however, some disadvantages of the K u band system. Around 10 GHz is the absorption peak due to orientation relaxation of molecules in liquid water. Above 10 GHz, Mie scattering takes over. The effect is a noticeable degradation, commonly known as rain fade , during heavy rain (100 mm/h). This problem can be mitigated by transmitting

1960-553: Is also possible to offer discontinuous coverage using a low-Earth-orbit satellite capable of storing data received while passing over one part of Earth and transmitting it later while passing over another part. This will be the case with the CASCADE system of Canada's CASSIOPE communications satellite. Another system using this store and forward method is Orbcomm . A medium Earth orbit is a satellite in orbit somewhere between 2,000 and 35,786 kilometres (1,243 and 22,236 mi) above

2058-521: Is also used as an inter-ethnic means of communication in some parts of Aceh province. Religion in Sumatra (2023) The majority of people in Sumatra are Muslims (87.12%), while 10.69% are Christians, and less than 2.19% are Buddhists and Hindus. Sumatra is one of seven geographical regions of Indonesia , which includes its adjacent smaller islands. Sumatra was one of the eight original provinces of Indonesia between 1945 and 1948. Including adjacent archipelagoes normally included with Sumatra (such as

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2156-443: Is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder ; it creates a communication channel between a source transmitter and a receiver at different locations on Earth . Communications satellites are used for television , telephone , radio , internet , and military applications. Many communications satellites are in geostationary orbit 22,236 miles (35,785 km) above

2254-471: Is carried out under the auspices of the International Telecommunication Union (ITU). To facilitate frequency planning, the world is divided into three regions: Within these regions, frequency bands are allocated to various satellite services, although a given service may be allocated different frequency bands in different regions. Some of the services provided by satellites are: The first and historically most important application for communication satellites

2352-492: Is highly inclined, guaranteeing good elevation over selected positions during the northern portion of the orbit. (Elevation is the extent of the satellite's position above the horizon. Thus, a satellite at the horizon has zero elevation and a satellite directly overhead has elevation of 90 degrees.) The Molniya orbit is designed so that the satellite spends the great majority of its time over the far northern latitudes, during which its ground footprint moves only slightly. Its period

2450-558: Is known as a satellite constellation . Two such constellations, intended to provide satellite phone and low-speed data services, primarily to remote areas, are the Iridium and Globalstar systems. The Iridium system has 66 satellites, which orbital inclination of 86.4° and inter-satellite links provide service availability over the entire surface of Earth. Starlink is a satellite internet constellation operated by SpaceX , that aims for global satellite Internet access coverage. It

2548-576: Is one half day, so that the satellite is available for operation over the targeted region for six to nine hours every second revolution. In this way a constellation of three Molniya satellites (plus in-orbit spares) can provide uninterrupted coverage. The first satellite of the Molniya series was launched on 23 April 1965 and was used for experimental transmission of TV signals from a Moscow uplink station to downlink stations located in Siberia and

2646-410: Is that a MEO satellite's distance gives it a longer time delay and weaker signal than a LEO satellite, although these limitations are not as severe as those of a GEO satellite. Like LEOs, these satellites do not maintain a stationary distance from the Earth. This is in contrast to the geostationary orbit, where satellites are always 35,786 kilometres (22,236 mi) from Earth. Typically the orbit of

2744-450: Is the ITU model. The DAH model has become an ITU recommendation since 2001 (Recommendation No. ITU-R P.618-7). This model can create a 99.7% available link so that K u -band can be applied in Indonesia. Use of the K u -band for satellite communications in tropical regions like Indonesia is becoming more frequent. Several satellites above Indonesia have K u -band transponders , and even K

2842-583: Is the largest producer of Indonesian coffee . Small-holders grow Arabica coffee ( Coffea arabica ) in the highlands, while Robusta ( Coffea canephora ) is found in the lowlands. Arabica coffee from the regions of Gayo, Lintong and Sidikilang is typically processed using the Giling Basah (wet hulling) technique, which gives it a heavy body and low acidity. Sumatra is a highly seismic island. Huge earthquakes have been recorded throughout history. In 1797, an 8.9 earthquake shook Western Sumatra, and in 1833,

2940-485: Is useful for communications because ground antennas can be aimed at the satellite without their having to track the satellite's motion. This is relatively inexpensive. In applications that require many ground antennas, such as DirecTV distribution, the savings in ground equipment can more than outweigh the cost and complexity of placing a satellite into orbit. By 2000, Hughes Space and Communications (now Boeing Satellite Development Center ) had built nearly 40 percent of

3038-529: The 2005 Nias–Simeulue earthquake and the 2010 Mentawai earthquake and tsunami . Lake Toba is the site of a supervolcanic eruption that occurred around 74,000 years ago, representing a climate-changing event. The most important rivers in Sumatra belong to the catchment area of the South China Sea . Heading north to south, the Asahan , Rokan , Siak , Kampar , Indragiri , Batanghari flow into

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3136-506: The 2013 Southeast Asian haze which caused considerable tensions between Indonesia and affected countries Malaysia and Singapore . The widespread deforestation and other environmental destruction in Sumatra and other parts of Indonesia has often been described by academics as an ecocide . Sumatra was known in ancient times by the Sanskrit names of Svarṇadvīpa ('Island of Gold') and Svarṇabhūmi ('Land of Gold'), because of

3234-404: The 2013 Southeast Asian haze which caused considerable tensions between Indonesia and affected countries Malaysia and Singapore . The widespread deforestation and other environmental destruction in Sumatra and other parts of Indonesia has often been described by academics as an ecocide . Several unconnected railway networks built during Netherlands East Indies exist in Sumatra, such as

3332-736: The Astra satellites. The 11.7 to 12.5 GHz segment is allocated to the BSS ( broadcasting satellite service ). Australia is part of ITU Region 3 and the Australian regulatory environment provides a class license that covers downlinking from 11.70 GHz to 12.75 GHz and uplinking from 14.0 GHz to 14.5 GHz. The ITU has categorized Indonesia as Region P, countries with very high rain precipitation. This statement has made many people unsure about using K u -band (11 – 18 GHz) in Indonesia. Using frequencies higher than 10 GHz in

3430-871: The Barisan Mountains in the west and swampy plains in the east. Sumatra is the closest Indonesian island to mainland Asia. To the southeast is Java , separated by the Sunda Strait . To the north is the Malay Peninsula (located on the Asian mainland), separated by the Strait of Malacca . To the east is Borneo , across the Karimata Strait . West of the island is the Indian Ocean . The Great Sumatran fault (a strike-slip fault), and

3528-569: The Earth-Moon-Libration points are also proposed for communication satellites covering the Moon alike communication satellites in geosynchronous orbit cover the Earth. Also, dedicated communication satellites in orbits around Mars supporting different missions on surface and other orbits are considered, such as the Mars Telecommunications Orbiter . Communications Satellites are usually composed of

3626-542: The Java Sea . The Bukit Barisan mountains, which contain several active volcanoes, form the backbone of the island, while the northeastern area contains large plains and lowlands with swamps, mangrove forest and complex river systems. The equator crosses the island at its centre in West Sumatra and Riau provinces. The climate of the island is tropical , hot, and humid. Lush tropical rain forest once dominated

3724-532: The Malacca Strait , while the island's largest river, the Musi , flows into the sea at Bangka Strait in the south. To the east, big rivers carry silt from the mountains, forming the vast lowland interspersed by swamps. Even if mostly unsuitable for farming, the area is currently of great economic importance for Indonesia. It produces oil from both above and below the soil – palm oil and petroleum . Sumatra

3822-587: The Rayleigh criterion , the diameter of a parabolic dish required to create a radiation pattern with a given angular beamwidth ( gain ) is proportional to the wavelength , and thus inversely proportional to the frequency. At 12 GHz a 1-meter dish is capable of focusing on one satellite while sufficiently rejecting the signal from another satellite only 2 degrees away. This is important because satellites in FSS (Fixed Satellite Service) service (11.7-12.2 GHz in

3920-584: The Second World War , Japan invaded Sumatra in 1942. The Free Aceh Movement fought against Indonesian government forces in the Aceh Insurgency from 1976 to 2005. Security crackdowns in 2001 and 2002 resulted in several thousand civilian deaths. The island was heavily impacted by both the 1883 Krakatoa eruption and the 2004 Boxing Day Tsunami . Sumatra’s population as of 2023 was estimated to be about 60,795,669 ; it has about

4018-577: The Sunda megathrust (a subduction zone ), run the entire length of the island along its west coast. On 26 December 2004, the western coast and islands of Sumatra, particularly Aceh province, were struck by a tsunami following the Indian Ocean earthquake . This was the longest earthquake recorded, lasting between 500 and 600 seconds (8.33–10 minutes). More than 170,000 Indonesians were killed, primarily in Aceh. Other recent earthquakes to strike Sumatra include

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4116-513: The equator , so that the satellite appears stationary at the same point in the sky; therefore the satellite dish antennas of ground stations can be aimed permanently at that spot and do not have to move to track the satellite. Others form satellite constellations in low Earth orbit , where antennas on the ground have to follow the position of the satellites and switch between satellites frequently. The radio waves used for telecommunications links travel by line of sight and so are obstructed by

4214-479: The 13th century. In terms of economic development the port of Banda Aceh only started to face competition in the 18th century when more ports were constructed in Sumatra for maritime transport . Nevertheless, major pepper suppliers used the port of Banda Aceh at the beginning of the 19th century. The port in Medan grew swiftly in the late 19th and early 20th century. Meanwhile the medium sized port of Palembang faced

4312-1250: The 2010 census (including Riau Islands , Bangka Belitung , Nias , Mentawai , Simeulue and islands around it) There are over 52 languages spoken, all of which (except Chinese and Tamil) belong to the Malayo-Polynesian branch of the Austronesian language family. Within Malayo-Polynesian, they are divided into several sub-branches: Chamic (which are represented by Acehnese in which its closest relatives are languages spoken by Ethnic Chams in Cambodia and Vietnam), Malayic ( Malay , Minangkabau and other closely related languages), Northwest Sumatra–Barrier Islands ( Batak languages , Gayo and others), Lampungic (includes Proper Lampung and Komering ) and Bornean (represented by Rejang in which its closest linguistic relatives are Bukar Sadong and Land Dayak spoken in West Kalimantan and Sarawak ( Malaysia )). Northwest Sumatra–Barrier Islands and Lampungic branches are endemic to

4410-477: The 6th and 7th centuries AD. At the beginning and end of the 13th century the formation of the kingdom, the king of the Samudra kingdom had converted to Islam. Marco Polo visited the island in 1292, and his fellow Italian Odoric of Pordenone in 1321. Aceh in the north of Sumatra became known in the 16th century as trading centre for the pepper trade by shipping quality piperaceae ( pepper ). Aceh became

4508-423: The Earth faster, they do not remain visible in the sky to a fixed point on Earth continually like a geostationary satellite, but appear to a ground observer to cross the sky and "set" when they go behind the Earth beyond the visible horizon. Therefore, to provide continuous communications capability with these lower orbits requires a larger number of satellites, so that one of these satellites will always be visible in

4606-415: The Earth's surface. MEO satellites are similar to LEO satellites in functionality. MEO satellites are visible for much longer periods of time than LEO satellites, usually between 2 and 8 hours. MEO satellites have a larger coverage area than LEO satellites. A MEO satellite's longer duration of visibility and wider footprint means fewer satellites are needed in a MEO network than a LEO network. One disadvantage

4704-563: The FSS ( fixed satellite service ), uplink from 14.0 to 14.5 GHz. There are more than 22 FSS K u band satellites orbiting over North America, each carrying 12 to 48 transponders , 20 to 120 watts per transponder, and requiring a 0.8-m to 1.5-m antenna for clear reception. The 12.2 to 12.7 GHz (LOF 11.25 to 11.75 GHz) segment is allocated to the BSS ( broadcasting satellite service ). BSS (DBS direct broadcast satellites ) normally carry 16 to 32 transponders of 27  MHz bandwidth running at 100 to 240 watts of power, allowing

4802-567: The Indonesian government announced a plan to protect Sumatra's remaining forests. The island includes more than 10 national parks, including three which are listed as the Tropical Rainforest Heritage of Sumatra World Heritage Site – Gunung Leuser National Park , Kerinci Seblat National Park and Bukit Barisan Selatan National Park . The Berbak National Park is one of three national parks in Indonesia listed as

4900-466: The K u band to the fixed service (microwave towers), radio astronomy service, space research service, mobile service, mobile satellite service, radiolocation service (radar), amateur radio service , and radionavigation. However, not all of these services are actually operating in this band and others are only minor users. Compared with C-band , K u band is not similarly restricted in power to avoid interference with terrestrial microwave systems, and

4998-474: The K u band. The Intelsat Americas 5 , Galaxy 10R and AMC 3 satellites over North America provide a quite large amount of FTA channels on their K u band transponders . Sumatra Sumatra ( / s ʊ ˈ m ɑː t r ə / ) is one of the Sunda Islands of western Indonesia . It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in

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5096-765: The Lincoln Laboratory on behalf of the United States Department of Defense . The LES-1 active communications satellite was launched on 11 February 1965 to explore the feasibility of active solid-state X band long-range military communications. A total of nine satellites were launched between 1965 and 1976 as part of this series. In the United States, 1962 saw the creation of the Communications Satellite Corporation (COMSAT) private corporation, which

5194-630: The Portuguese throughout the 16th and 17th century. When the Dutch were weakened in the 18th century the British empire began to actively intervene in Aceh, establishing close relations between Banda Aceh and Penang . In the 17th and 18th century the Aceh Sultanate battled the Siak sultanate in the south of Sumatra. The port city of Banda Aceh was recorded in European historical writings since

5292-563: The Riau Islands, Nias and the Bangka-Belitung group), it now covers ten of Indonesia's 38 provinces , which are set out below with their areas and populations. The longest axis of the island runs approximately 1,790 km (1,110 mi) northwest–southeast, crossing the equator near the centre. At its widest point, the island spans 435 km (270 mi). The interior of the island is dominated by two geographical regions:

5390-800: The Russian Far East, in Norilsk , Khabarovsk , Magadan and Vladivostok . In November 1967 Soviet engineers created a unique system of national TV network of satellite television , called Orbita , that was based on Molniya satellites. In the United States, the National Polar-orbiting Operational Environmental Satellite System (NPOESS) was established in 1994 to consolidate the polar satellite operations of NASA (National Aeronautics and Space Administration) NOAA (National Oceanic and Atmospheric Administration). NPOESS manages

5488-520: The U.S.) are only 2 degrees apart. At 4 GHz (C-band) a 3-meter dish is required to achieve this narrow angular resolution. Note the inverse linear correlation between dish size and frequency. For K u satellites in DBS (Direct Broadcast Satellite) service (12.2-12.7 GHz in the U.S.) dishes much smaller than 1-meter can be used because those satellites are spaced 9 degrees apart. As power levels on both C and K u band satellites have increased over

5586-496: The antenna's actual receiving element, mounted in front of the dish (and pointed back towards its face); if the waves are more intense, fewer of them need to be collected to achieve the same intensity at the receiving element. A major attraction of the band over lower frequency microwave bands is that the shorter wavelengths allow sufficient angular resolution to separate the signals of different communication satellites to be achieved with smaller terrestrial parabolic antennas . From

5684-403: The completion of a fully global network with Intelsat 3 in 1969–70. By the 1980s, with significant expansions in commercial satellite capacity, Intelsat was on its way to become part of the competitive private telecommunications industry, and had started to get competition from the likes of PanAmSat in the United States, which, ironically, was then bought by its archrival in 2005. When Intelsat

5782-462: The curve of the Earth. The purpose of communications satellites is to relay the signal around the curve of the Earth allowing communication between widely separated geographical points. Communications satellites use a wide range of radio and microwave frequencies . To avoid signal interference, international organizations have regulations for which frequency ranges or "bands" certain organizations are allowed to use. This allocation of bands minimizes

5880-619: The dipoles properly separated from each other, the project was able to successfully experiment and communicate using frequencies in the SHF X band spectrum. An immediate antecedent of the geostationary satellites was the Hughes Aircraft Company 's Syncom 2 , launched on 26 July 1963. Syncom 2 was the first communications satellite in a geosynchronous orbit . It revolved around the Earth once per day at constant speed, but because it still had north–south motion, special equipment

5978-455: The edges of Antarctica and Greenland . Other land use for satellite phones are rigs at sea, a backup for hospitals, military, and recreation. Ships at sea, as well as planes, often use satellite phones. Satellite phone systems can be accomplished by a number of means. On a large scale, often there will be a local telephone system in an isolated area with a link to the telephone system in a main land area. There are also services that will patch

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6076-605: The entire island. By the year 692 , the Melayu Kingdom was absorbed by Srivijaya . Srivijaya's influence waned in the 11th century, specifically in the year 1025, after suffering defeat at the hands of the Chola Empire in southern India By the end of the 12th century, Srivijaya had been reduced to a kingdom, and its dominant role in South Sumatra ended with the last king, Ratu Sekekhummong, who founded

6174-692: The equator and therefore appear lower on the horizon as the receiver gets farther from the equator. This will cause problems for extreme northerly latitudes, affecting connectivity and causing multipath interference (caused by signals reflecting off the ground and into the ground antenna). Thus, for areas close to the North (and South) Pole, a geostationary satellite may appear below the horizon. Therefore, Molniya orbit satellites have been launched, mainly in Russia, to alleviate this problem. Molniya orbits can be an appealing alternative in such cases. The Molniya orbit

6272-473: The first artificial satellite used for passive relay communications in Echo 1 on 12 August 1960. Echo 1 was an aluminized balloon satellite acting as a passive reflector of microwave signals. Communication signals were bounced off the satellite from one point on Earth to another. This experiment sought to establish the feasibility of worldwide broadcasts of telephone, radio, and television signals. Telstar

6370-412: The first privately sponsored space launch. Another passive relay experiment primarily intended for military communications purposes was Project West Ford , which was led by Massachusetts Institute of Technology 's Lincoln Laboratory . After an initial failure in 1961, a launch on 9 May 1963 dispersed 350 million copper needle dipoles to create a passive reflecting belt. Even though only about half of

6468-479: The following subsystems: The bandwidth available from a satellite depends upon the number of transponders provided by the satellite. Each service (TV, Voice, Internet, radio) requires a different amount of bandwidth for transmission. This is typically known as link budgeting and a network simulator can be used to arrive at the exact value. Allocating frequencies to satellite services is a complicated process which requires international coordination and planning. This

6566-412: The gold deposits in the island's highlands . The earliest known mention of the current form "Sumatra" was in 1017, when the local king Haji Sumatrabhumi ("king of the land of Sumatra") sent an envoy to China . Arab geographers referred to the island as Lamri ( Lamuri , Lambri or Ramni ) in the tenth through thirteenth centuries, in reference to a kingdom near modern-day Banda Aceh which

6664-404: The ground, do not require as high signal strength (signal strength falls off as the square of the distance from the source, so the effect is considerable). Thus there is a trade off between the number of satellites and their cost. In addition, there are important differences in the onboard and ground equipment needed to support the two types of missions. A group of satellites working in concert

6762-626: The island. Like all parts of Indonesia, Indonesian (which was based on Riau Malay) is the official language and the main lingua franca. Although Sumatra has its own local lingua franca, variants of Malay like Medan Malay and Palembang Malay are popular in North and South Sumatra, especially in urban areas. Minangkabau (Padang dialect) is popular in West Sumatra, some parts of North Sumatra, Bengkulu, Jambi and Riau (especially in Pekanbaru and areas bordered with West Sumatra ) while Acehnese

6860-399: The kingdom as Samara , while his contemporary fellow Italian traveller Odoric of Pordenone used the form Sumoltra . Later in the 14th century the local form "Sumatra" became popular abroad due to the rising power of the kingdom of Samudera Pasai and the subsequent Sultanate of Aceh . From then on, subsequent European writers mostly used Sumatra or similar forms of the name for

6958-447: The landscape. Sumatra has a wide range of plant and animal species but has lost almost 50% of its tropical rainforest in the last 35 years. Many species are now critically endangered , such as the Sumatran ground cuckoo , the Sumatran tiger , the Sumatran elephant , the Sumatran rhinoceros , and the Sumatran orangutan . Deforestation on the island has also resulted in serious seasonal smoke haze over neighbouring countries, such as

7056-515: The late 20th century. Satellite communications are still used in many applications today. Remote islands such as Ascension Island , Saint Helena , Diego Garcia , and Easter Island , where no submarine cables are in service, need satellite telephones. There are also regions of some continents and countries where landline telecommunications are rare to non existent, for example large regions of South America, Africa, Canada, China, Russia, and Australia. Satellite communications also provide connection to

7154-643: The main commercial centre of the Aceh Sultanate and trading routes were established to the Mediterranean via the Red Sea to rival the Portuguese shipping lanes . The reign of Iskandar Muda is known as the golden age of Sumatra because he extended the cultural influence of the Aceh Sultanate to Padang and Johor . The Aceh Sultanate sustained the rivalry with the Johor sultanate , the Dutch, and

7252-457: The milestone of Kepaksian Sekala Brak in the 13th century AD with the Dalom building. At the same time, the spread of Islam in Indonesia occurred gradually and indirectly, starting from the western regions such as the Sumatra area which became the first place for the spread of Islam in the archipelago, then Java, then to the eastern regions of Indonesia, Sulawesi and Maluku. The island of Sumatra

7350-566: The more than one hundred satellites in service worldwide. Other major satellite manufacturers include Space Systems/Loral , Orbital Sciences Corporation with the Star Bus series, Indian Space Research Organisation , Lockheed Martin (owns the former RCA Astro Electronics/GE Astro Space business), Northrop Grumman , Alcatel Space, now Thales Alenia Space , with the Spacebus series, and Astrium . Geostationary satellites must operate above

7448-416: The nearby Mentawai Islands . There are about 300 freshwater fish species in Sumatra. There are 93 amphibian species in Sumatra, 21 of which are endemic to Sumatra. The Sumatran tiger , Sumatran rhinoceros , Sumatran elephant , Sumatran ground cuckoo , Sumatran orangutan and Tapanuli orangutan are all critically endangered, indicating the highest level of threat to their survival. In October 2008,

7546-470: The northern hemisphere. This orbit provides a long dwell time over Russian territory as well as over Canada at higher latitudes than geostationary orbits over the equator. Communications satellites usually have one of three primary types of orbit , while other orbital classifications are used to further specify orbital details. MEO and LEO are non-geostationary orbit (NGSO). As satellites in MEO and LEO orbit

7644-564: The other hand, amplify the received signal before retransmitting it to the receiver on the ground. Passive satellites were the first communications satellites, but are little used now. Work that was begun in the field of electrical intelligence gathering at the United States Naval Research Laboratory in 1951 led to a project named Communication Moon Relay . Military planners had long shown considerable interest in secure and reliable communications lines as

7742-410: The power of its uplinks and downlinks can be increased. This higher power also translates into smaller receiving dishes and points out a generalization between a satellite's transmission and a dish's size. As the power increases, the size of an antenna's dish will decrease. This is because the purpose of the dish element of the antenna is to collect the incident waves over an area and focus them all onto

7840-432: The risk of signal interference. In October 1945, Arthur C. Clarke published an article titled "Extraterrestrial Relays" in the British magazine Wireless World . The article described the fundamentals behind the deployment of artificial satellites in geostationary orbits to relay radio signals. Because of this, Arthur C. Clarke is often quoted as being the inventor of the concept of the communications satellite, and

7938-996: The same linear polarization as FSS-class satellites. Examples of these are the Astra , Eutelsat , and Hotbird spacecraft in orbit over the European continent. Because of this, the terms FSS and DBS are more so used throughout the North American continent, and are uncommon in Europe. Fixed Service Satellites use the C band , and the lower portions of the K u band . They are normally used for broadcast feeds to and from television networks and local affiliate stations (such as program feeds for network and syndicated programming, live shots , and backhauls ), as well as being used for distance learning by schools and universities, business television (BTV), Videoconferencing , and general commercial telecommunications. FSS satellites are also used to distribute national cable channels to cable television headends. Free-to-air satellite TV channels are also usually distributed on FSS satellites in

8036-473: The same number of inhabitants as South Africa , making it the fifth-most populous island in the world . Yet because it is such a large island, it is not densely populated: it has an average of about 126 people per km . The largest indigenous ethnic groups in Sumatra are Malays, Minangkabaus, Bataks, Acehnese, and Lampungs. Other major non-indigenous ethnic groups are Javanese , Sundanese , and Chinese . Below are 11 largest ethnic groups in Sumatra based on

8134-408: The signal coming from the source, toward the direction of the receiver. With passive satellites, the reflected signal is not amplified at the satellite, and only a small amount of the transmitted energy actually reaches the receiver. Since the satellite is so far above Earth, the radio signal is attenuated due to free-space path loss , so the signal received on Earth is very weak. Active satellites, on

8232-402: The sky for transmission of communication signals. However, due to their closer distance to the Earth, LEO or MEO satellites can communicate to ground with reduced latency and at lower power than would be required from a geosynchronous orbit. A low Earth orbit (LEO) typically is a circular orbit about 160 to 2,000 kilometres (99 to 1,243 mi) above the Earth's surface and, correspondingly,

8330-590: The term 'Clarke Belt' is employed as a description of the orbit. The first artificial Earth satellite was Sputnik 1 , which was put into orbit by the Soviet Union on 4 October 1957. It was developed by Mikhail Tikhonravov and Sergey Korolev , building on work by Konstantin Tsiolkovsky . Sputnik 1 was equipped with an on-board radio transmitter that worked on two frequencies of 20.005 and 40.002 MHz, or 7 and 15 meters wavelength. The satellite

8428-454: The use of receiver antennas as small as 18 inches (450 mm). Segments in those regions are represented by ITU Region 1, and they are the 11.45 to 11.7 and 12.5 to 12.75 GHz bands are allocated to the FSS ( fixed satellite service , uplink 14.0 to 14.5 GHz). In Europe K u band is used from 10.7 to 12.75 GHz (LOF Low 9.75 GHz, LOF High 10.6 GHz) for direct broadcast satellite services such as those carried by

8526-626: The western coast. In the northeast, the narrow Strait of Malacca separates the island from the Malay Peninsula , which is an extension of the Eurasian continent. In the southeast, the narrow Sunda Strait , containing the Krakatoa Archipelago , separates Sumatra from Java . The northern tip of Sumatra is near the Andaman Islands , while off the southeastern coast lie the islands of Bangka and Belitung, Karimata Strait and

8624-489: The world at 482,286.55 km (182,812 mi. ), including adjacent islands such as the Simeulue , Nias , Mentawai , Enggano , Riau Islands , Bangka Belitung and Krakatoa archipelago . Sumatra is an elongated landmass spanning a diagonal northwest–southeast axis. The Indian Ocean borders the northwest, west, and southwest coasts of Sumatra, with the island chain of Simeulue , Nias , Mentawai , and Enggano off

8722-402: The years, dish beam-width has become much more critical than gain. The K u band also offers a user more flexibility. A smaller dish size and a K u band system's freedom from terrestrial operations simplifies finding a suitable dish site. For the end users K u band is generally cheaper and enables smaller antennas (both because of the higher frequency and a more focused beam). K u band

8820-515: Was Project SCORE , led by Advanced Research Projects Agency (ARPA) and launched on 18 December 1958, which used a tape recorder to carry a stored voice message, as well as to receive, store, and retransmit messages. It was used to send a Christmas greeting to the world from U.S. President Dwight D. Eisenhower . The satellite also executed several realtime transmissions before the non-rechargeable batteries failed on 30 December 1958 after eight hours of actual operation. The direct successor to SCORE

8918-429: Was another ARPA-led project called Courier. Courier 1B was launched on 4 October 1960 to explore whether it would be possible to establish a global military communications network by using "delayed repeater" satellites, which receive and store information until commanded to rebroadcast them. After 17 days, a command system failure ended communications from the satellite. NASA 's satellite applications program launched

9016-428: Was in intercontinental long distance telephony . The fixed Public Switched Telephone Network relays telephone calls from land line telephones to an Earth station , where they are then transmitted to a geostationary satellite. The downlink follows an analogous path. Improvements in submarine communications cables through the use of fiber-optics caused some decline in the use of satellites for fixed telephony in

9114-492: Was launched, the United States was the only launch source outside of the Soviet Union , who did not participate in the Intelsat agreements. The Soviet Union launched its first communications satellite on 23 April 1965 as part of the Molniya program. This program was also unique at the time for its use of what then became known as the Molniya orbit , which describes a highly elliptical orbit , with two high apogees daily over

9212-493: Was needed to track it. Its successor, Syncom 3 , launched on 19 July 1964, was the first geostationary communications satellite. Syncom 3 obtained a geosynchronous orbit, without a north–south motion, making it appear from the ground as a stationary object in the sky. A direct extension of the passive experiments of Project West Ford was the Lincoln Experimental Satellite program, also conducted by

9310-500: Was not placed in orbit to send data from one point on Earth to another, but the radio transmitter was meant to study the properties of radio wave distribution throughout the ionosphere. The launch of Sputnik 1 was a major step in the exploration of space and rocket development, and marks the beginning of the Space Age . There are two major classes of communications satellites, passive and active . Passive satellites only reflect

9408-644: Was subject to instruction by the US Government on matters of national policy. Over the next two years, international negotiations led to the Intelsat Agreements, which in turn led to the launch of Intelsat 1, also known as Early Bird, on 6 April 1965, and which was the first commercial communications satellite to be placed in geosynchronous orbit. Subsequent Intelsat launches in the 1960s provided multi-destination service and video, audio, and data service to ships at sea (Intelsat 2 in 1966–67), and

9506-591: Was the first active, direct relay communications commercial satellite and marked the first transatlantic transmission of television signals. Belonging to AT&T as part of a multi-national agreement between AT&T, Bell Telephone Laboratories , NASA, the British General Post Office , and the French National PTT (Post Office) to develop satellite communications, it was launched by NASA from Cape Canaveral on 10 July 1962, in

9604-557: Was the first landfall for traders. The island has also been known by other names, including Andalas or Percha Island . Scholars suggest that mention of Suwarnadwipa in the Hindu Epic the Ramayana may be a reference to Sumatra. According to experts on The Ramayana , the epic is one of the first sources to document the relationship between India and the Indonesian archipelago. In the late 13th century, Marco Polo referred to

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