The Caribbean is a region of The Americas that consists of the Caribbean Sea, its islands and the surrounding coasts. The region is southeast of the Gulf of Mexico and the North American mainland, east of Central America, north of South America. Situated on the Caribbean Plate, the region comprises more than 700 islands, islets and cays; these islands form island arcs that delineate the eastern and northern edges of the Caribbean Sea. The Caribbean islands, consisting of the Greater Antilles on the north and the Lesser Antilles on the south and east, are part of the somewhat larger West Indies grouping, which includes the Lucayan Archipelago; the Lucayans and, less Bermuda, are sometimes considered Caribbean despite the fact that none of these islands border the Caribbean Sea. In a wider sense, the mainland countries and territories of Belize, the Caribbean region of Colombia, the Yucatán Peninsula, Margarita Island, the Guyanas, are included due to their political and cultural ties with the region.
Geopolitically, the Caribbean islands are regarded as a subregion of North America and are organized into 30 territories including sovereign states, overseas departments, dependencies. From December 15, 1954, to October 10, 2010, there was a country known as the Netherlands Antilles composed of five states, all of which were Dutch dependencies. From January 3, 1958, to May 31, 1962, there was a short-lived political union called the West Indies Federation composed of ten English-speaking Caribbean territories, all of which were British dependencies; the West Indies cricket team continues to represent many of those nations. The region takes its name from that of the Caribs, an ethnic group present in the Lesser Antilles and parts of adjacent South America at the time of the Spanish conquest of the Americas; the two most prevalent pronunciations of "Caribbean" outside the Caribbean are, with the primary stress on the third syllable, with the stress on the second. Most authorities of the last century preferred the stress on the third syllable.
This is the older of the two pronunciations, but the stressed-second-syllable variant has been established for over 75 years. It has been suggested that speakers of British English prefer while North American speakers more use, but major American dictionaries and other sources list the stress on the third syllable as more common in American English too. According to the American version of Oxford Online Dictionaries, the stress on the second syllable is becoming more common in UK English and is considered "by some" to be more up to date and more "correct"; the Oxford Online Dictionaries claim that the stress on the second syllable is the most common pronunciation in the Caribbean itself, but according to the Dictionary of Caribbean English Usage, the most common pronunciation in Caribbean English stresses the first syllable instead. The word "Caribbean" has multiple uses, its principal ones are political. The Caribbean can be expanded to include territories with strong cultural and historical connections to slavery, European colonisation and the plantation system.
The United Nations geoscheme for the Americas presents the Caribbean as a distinct region within the Americas. Physiographically, the Caribbean region is a chain of islands surrounding the Caribbean Sea. To the north, the region is bordered by the Gulf of Mexico, the Straits of Florida and the Northern Atlantic Ocean, which lies to the east and northeast. To the south lies the coastline of the continent of South America. Politically, the "Caribbean" may be centred on socio-economic groupings found in the region. For example, the bloc known as the Caribbean Community contains the Co-operative Republic of Guyana, the Republic of Suriname in South America and Belize in Central America as full members. Bermuda and the Turks and Caicos Islands, which are in the Atlantic Ocean, are associate members of the Caribbean Community; the Commonwealth of the Bahamas is in the Atlantic and is a full member of the Caribbean Community. Alternatively, the organisation called the Association of Caribbean States consists of every nation in the surrounding regions that lie on the Caribbean, plus El Salvador, which lies on the Pacific Ocean.
According to the ACS, the total population of its member states is 227 million people. The geography and climate in the Caribbean region varies: Some islands in the region have flat terrain of non-volcanic origin; these islands include Aruba, Curaçao, Bonaire, the Cayman Islands, Saint Croix, the Bahamas, Antigua. Others possess rugged towering mountain-ranges like the islands of Saint Martin, Hispaniola, Puerto Rico, Dominica, Saba, Sint Eustatius, Saint Kitts, Saint Lucia, Saint Thomas, Saint John, Grenada, Saint Vincent, Guadeloupe and Trinidad and Tobago. Definitions of the terms Greater Antilles and Lesser Antilles vary; the Virgin Islands as part of the Puerto Rican bank are sometimes included with the Greater Antilles. The term Lesser Antilles is used to define an island arc that includes Grenada but excludes Trinidad and Tobago and the Leeward Antilles; the waters of the Caribbean Sea host large, migratory schools of fish and coral reef
General Packet Radio Service
General Packet Radio Service is a packet oriented mobile data standard on the 2G and 3G cellular communication network's global system for mobile communications. GPRS was established by European Telecommunications Standards Institute in response to the earlier CDPD and i-mode packet-switched cellular technologies, it is now maintained by the 3rd Generation Partnership Project. GPRS is sold according to the total volume of data transferred during the billing cycle, in contrast with circuit switched data, billed per minute of connection time, or sometimes by one-third minute increments. Usage above the GPRS bundled data cap may be charged per MB of data, speed disallowed. GPRS is a best-effort service, implying variable throughput and latency that depend on the number of other users sharing the service concurrently, as opposed to circuit switching, where a certain quality of service is guaranteed during the connection. In 2G systems, GPRS provides data rates of 56–114 kbit/sec. 2G cellular technology combined with GPRS is sometimes described as 2.5G, that is, a technology between the second and third generations of mobile telephony.
It provides moderate-speed data transfer, by using unused time division multiple access channels in, for example, the GSM system. GPRS is integrated into GSM Release 97 and newer releases; the GPRS core network allows 2G, 3G and WCDMA mobile networks to transmit IP packets to external networks such as the Internet. The GPRS system is an integrated part of the GSM network switching subsystem. GPRS extends the GSM Packet circuit switched data capabilities and makes the following services possible: SMS messaging and broadcasting "Always on" internet access Multimedia messaging service Push-to-talk over cellular Instant messaging and presence—wireless village Internet applications for smart devices through wireless application protocol Point-to-point service: inter-networking with the Internet Point-to-multipoint service: point-to-multipoint multicast and point-to-multipoint group callsIf SMS over GPRS is used, an SMS transmission speed of about 30 SMS messages per minute may be achieved; this is much faster than using the ordinary SMS over GSM, whose SMS transmission speed is about 6 to 10 SMS messages per minute.
GPRS supports the following protocols: Internet Protocol. In practice, built-in mobile browsers use IPv4. Point-to-Point Protocol is not supported by mobile phone operators but if a cellular phone is used as a modem for a connected computer, PPP may be used to tunnel IP to the phone; this allows an IP address to be dynamically assigned to the mobile equipment. X.25 connections are used for applications like wireless payment terminals, although it has been removed from the standard. X.25 can still be supported over PPP, or over IP, but this requires either a network-based router to perform encapsulation or software built into the end-device/terminal. When TCP/IP is used, each phone can have one or more IP addresses allocated. GPRS will store and forward the IP packets to the phone during handover; the TCP restores. Devices supporting GPRS are grouped into three classes: Class A Can be connected to GPRS service and GSM service simultaneously; such devices are now available. Class B Can be connected to GPRS service and GSM service.
During GSM service, GPRS service is suspended and resumed automatically after the GSM service has concluded. Most GPRS mobile devices are Class B. Class C Are connected to either GPRS service or GSM service and must be switched manually between one service and the other; because a Class A device must service GPRS and GSM networks together, it needs two radios. To avoid this hardware requirement, a GPRS mobile device may implement the dual transfer mode feature. A DTM-capable mobile can handle both GSM packets and GPRS packets with network coordination to ensure both types are not transmitted at the same time; such devices are considered pseudo-Class A, sometimes referred to as "simple class A". Some networks have supported DTM since 2007. USB 3G/GPRS modems have a terminal-like interface over USB with V.42bis, RFC 1144 data formats. Some models include an external antenna connector. Modem cards for laptop PCs, or external USB modems are available, similar in shape and size to a computer mouse, or a pendrive.
A GPRS connection is established by reference to its access point name. The APN defines the services such as wireless application protocol access, short message service, multimedia messaging service, for Internet communication services such as email and World Wide Web access. In order to set up a GPRS connection for a wireless modem, a user must specify an APN, optionally a user name and password, rarely an IP address, provided by the network operator. GSM module or GPRS modules are similar to modems, but there’s one difference: the modem is an external piece of equipment, whereas the GSM module or GPRS module can be integrated within an electrical or electronic equipment, it is an embedded piece of hardware. A GSM mobile, on the other hand, is a complete embedded system in itself, it comes with embedded processors dedicated to provide a functional interface between the user and the mobile network. The upload and download speeds that can be achieved in GPRS depend on a number of factors such as: the number of BTS TDMA time slots assigned by the operator the channel encoding used.
The maximum capability of the mobile device expressed as a GPRS multislot class
The Universal Mobile Telecommunications System is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP, UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS uses wideband code division multiple access radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators. UMTS specifies a complete network system, which includes the radio access network, the core network and the authentication of users via SIM cards; the technology described in UMTS is sometimes referred to as Freedom of Mobile Multimedia Access or 3GSM. Unlike EDGE and CDMA2000, UMTS requires new base stations and new frequency allocations. UMTS supports maximum theoretical data transfer rates of 42 Mbit/s when Evolved HSPA is implemented in the network. Users in deployed networks can expect a transfer rate of up to 384 kbit/s for Release'99 handsets, 7.2 Mbit/s for High-Speed Downlink Packet Access handsets in the downlink connection.
These speeds are faster than the 9.6 kbit/s of a single GSM error-corrected circuit switched data channel, multiple 9.6 kbit/s channels in High-Speed Circuit-Switched Data and 14.4 kbit/s for CDMAOne channels. Since 2006, UMTS networks in many countries have been or are in the process of being upgraded with High-Speed Downlink Packet Access, sometimes known as 3.5G. HSDPA enables downlink transfer speeds of up to 21 Mbit/s. Work is progressing on improving the uplink transfer speed with the High-Speed Uplink Packet Access. Longer term, the 3GPP Long Term Evolution project plans to move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up, using a next generation air interface technology based upon orthogonal frequency-division multiplexing; the first national consumer UMTS networks launched in 2002 with a heavy emphasis on telco-provided mobile applications such as mobile TV and video calling. The high data speeds of UMTS are now most utilised for Internet access: experience in Japan and elsewhere has shown that user demand for video calls is not high, telco-provided audio/video content has declined in popularity in favour of high-speed access to the World Wide Web—either directly on a handset or connected to a computer via Wi-Fi, Bluetooth or USB.
UMTS combines three different terrestrial air interfaces, GSM's Mobile Application Part core, the GSM family of speech codecs. The air interfaces are called UMTS Terrestrial Radio Access. All air interface options are part of ITU's IMT-2000. In the most popular variant for cellular mobile telephones, W-CDMA is used, it is called "Uu interface", as it links User Equipment to the UMTS Terrestrial Radio Access Network Please note that the terms W-CDMA, TD-CDMA and TD-SCDMA are misleading. While they suggest covering just a channel access method, they are the common names for the whole air interface standards. W-CDMA or WCDMA, along with UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface standard found in 3G mobile telecommunications networks, it supports conventional cellular voice, text and MMS services, but can carry data at high speeds, allowing mobile operators to deliver higher bandwidth applications including streaming and broadband Internet access. W-CDMA uses the DS-CDMA channel access method with a pair of 5 MHz wide channels.
In contrast, the competing CDMA2000 system uses one or more available 1.25 MHz channels for each direction of communication. W-CDMA systems are criticized for their large spectrum usage, which delayed deployment in countries that acted slowly in allocating new frequencies for 3G services; the specific frequency bands defined by the UMTS standard are 1885–2025 MHz for the mobile-to-base and 2110–2200 MHz for the base-to-mobile. In the US, 1710–1755 MHz and 2110–2155 MHz are used instead, as the 1900 MHz band was used. While UMTS2100 is the most deployed UMTS band, some countries' UMTS operators use the 850 MHz and/or 1900 MHz bands, notably in the US by AT&T Mobility, New Zealand by Telecom New Zealand on the XT Mobile Network and in Australia by Telstra on the Next G network; some carriers such as T-Mobile use band numbers to identify the UMTS frequencies. For example, Band I, Band IV, Band V. UMTS-FDD is an acronym for Universal Mobile Telecommunications System - frequency-division duplexing and a 3GPP standardized version of UMTS networks that makes use of frequency-division duplexing for duplexing over an UMTS Terrestrial Radio Access air interface.
W-CDMA is the basis of Japan's NTT DoCoMo's FOMA service and the most-commonly used member of the Universal Mobile Telecommunications System family and sometimes used as a synonym for UMTS. It uses the DS-CDMA channel access method and the FDD duplexing method to achieve higher speeds and support more users compared to most used time division multiple access and time division duplex schemes. While not an evolutionary upgrade on the airside, it uses the same core network as the 2G GSM networks deployed worldwide, allowing dual mode mobile operation al
The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 square kilometers. It covers 20 percent of the Earth's surface and about 29 percent of its water surface area, it separates the "Old World" from the "New World". The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, the Americas to the west; as one component of the interconnected global ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, the Southern Ocean in the south. The Equatorial Counter Current subdivides it into the North Atlantic Ocean and the South Atlantic Ocean at about 8°N. Scientific explorations of the Atlantic include the Challenger expedition, the German Meteor expedition, Columbia University's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office; the oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC: Atlantikoi pelágei and in The Histories of Herodotus around 450 BC: Atlantis thalassa where the name refers to "the sea beyond the pillars of Heracles", said to be part of the sea that surrounds all land.
Thus, on one hand, the name refers to Atlas, the Titan in Greek mythology, who supported the heavens and who appeared as a frontispiece in Medieval maps and lent his name to modern atlases. On the other hand, to early Greek sailors and in Ancient Greek mythological literature such as the Iliad and the Odyssey, this all-encompassing ocean was instead known as Oceanus, the gigantic river that encircled the world. In contrast, the term "Atlantic" referred to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast; the Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of millions of years ago. The term "Aethiopian Ocean", derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century. During the Age of Discovery, the Atlantic was known to English cartographers as the Great Western Ocean; the term The Pond is used by British and American speakers in context to the Atlantic Ocean, as a form of meiosis, or sarcastic understatement.
The term dates to as early as 1640, first appearing in print in pamphlet released during the reign of Charles I, reproduced in 1869 in Nehemiah Wallington's Historical Notices of Events Occurring Chiefly in The Reign of Charles I, where "great Pond" is used in reference to the Atlantic Ocean by Francis Windebank, Charles I's Secretary of State. The International Hydrographic Organization defined the limits of the oceans and seas in 1953, but some of these definitions have been revised since and some are not used by various authorities and countries, see for example the CIA World Factbook. Correspondingly, the extent and number of oceans and seas varies; the Atlantic Ocean is bounded on the west by South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. To the east, the boundaries of the ocean proper are Europe: the Strait of Africa. In the southeast, the Atlantic merges into the Indian Ocean; the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border.
In the 1953 definition it extends south to Antarctica, while in maps it is bounded at the 60° parallel by the Southern Ocean. The Atlantic has irregular coasts indented by numerous bays and seas; these include the Baltic Sea, Black Sea, Caribbean Sea, Davis Strait, Denmark Strait, part of the Drake Passage, Gulf of Mexico, Labrador Sea, Mediterranean Sea, North Sea, Norwegian Sea all of the Scotia Sea, other tributary water bodies. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23.5% of the global ocean and has a volume of 310,410,900 km3 or 23.3% of the total volume of the earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3; the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the Milwaukee Deep in the Puerto Rico Trench, is 8,486 m.
The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S; the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2,000 m along most of its length, but is interrupted by larger transform faults at two places: the Romanche Trench near the Equator and the Gibbs Fracture Zone at 53°N; the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the othe
Mexico the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States. Covering 2,000,000 square kilometres, the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the eleventh most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity, the capital city and its most populous city. Other metropolises in the state include Guadalajara, Puebla, Tijuana and León. Pre-Columbian Mexico dates to about 8000 BC and is identified as one of five cradles of civilization and was home to many advanced Mesoamerican civilizations such as the Olmec, Teotihuacan, Zapotec and Aztec before first contact with Europeans. In 1521, the Spanish Empire conquered and colonized the territory from its politically powerful base in Mexico-Tenochtitlan, administered as the viceroyalty of New Spain.
Three centuries the territory became a nation state following its recognition in 1821 after the Mexican War of Independence. The post-independence period was tumultuous, characterized by economic inequality and many contrasting political changes; the Mexican–American War led to a territorial cession of the extant northern territories to the United States. The Pastry War, the Franco-Mexican War, a civil war, two empires, the Porfiriato occurred in the 19th century; the Porfiriato was ended by the start of the Mexican Revolution in 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the country's current political system as a federal, democratic republic. Mexico has the 11th largest by purchasing power parity; the Mexican economy is linked to those of its 1994 North American Free Trade Agreement partners the United States. In 1994, Mexico became the first Latin American member of the Organisation for Economic Co-operation and Development, it is classified as an upper-middle income country by the World Bank and a newly industrialized country by several analysts.
The country is considered both a regional power and a middle power, is identified as an emerging global power. Due to its rich culture and history, Mexico ranks first in the Americas and seventh in the world for number of UNESCO World Heritage Sites. Mexico is an ecologically megadiverse country, ranking fourth in the world for its biodiversity. Mexico receives a huge number of tourists every year: in 2018, it was the sixth most-visited country in the world, with 39 million international arrivals. Mexico is a member of the United Nations, the World Trade Organization, the G8+5, the G20, the Uniting for Consensus group of the UN, the Pacific Alliance trade bloc. Mēxihco is the Nahuatl term for the heartland of the Aztec Empire, namely the Valley of Mexico and surrounding territories, with its people being known as the Mexica, it is believed to be a toponym for the valley which became the primary ethnonym for the Aztec Triple Alliance as a result, although it could have been the other way around.
In the colonial era, back when Mexico was called New Spain this territory became the Intendency of Mexico and after New Spain achieved independence from the Spanish Empire it came to be known as the State of Mexico with the new country being named after its capital: the City of Mexico, which itself was founded in 1524 on top of the ancient Mexica capital of Mexico-Tenochtitlan. Traditionally, the name Tenochtitlan was thought to come from Nahuatl tetl and nōchtli and is thought to mean "Among the prickly pears rocks". However, one attestation in the late 16th-century manuscript known as "the Bancroft dialogues" suggests the second vowel was short, so that the true etymology remains uncertain; the suffix -co is the Nahuatl locative, making the word a place name. Beyond that, the etymology is uncertain, it has been suggested that it is derived from Mextli or Mēxihtli, a secret name for the god of war and patron of the Mexica, Huitzilopochtli, in which case Mēxihco means "place where Huitzilopochtli lives".
Another hypothesis suggests that Mēxihco derives from a portmanteau of the Nahuatl words for "moon" and navel. This meaning might refer to Tenochtitlan's position in the middle of Lake Texcoco; the system of interconnected lakes, of which Texcoco formed the center, had the form of a rabbit, which the Mesoamericans pareidolically associated with the moon rabbit. Still another hypothesis suggests that the word is derived from Mēctli, the name of the goddess of maguey; the name of the city-state was transliterated to Spanish as México with the phonetic value of the letter x in Medieval Spanish, which represented the voiceless postalveolar fricative. This sound, as well as the voiced postalveolar fricative, represented by a j, evolved into a voiceless velar fricative during the 16th century; this led to the use of the variant Méjico in many publications in Spanish, most notably in Spain, whereas in Mexico and most other Spanish–speaking countries, México was the preferred spelling. In recent years, the Real Academia Española, which regulates the Spanish l
Microwave transmission is the transmission of information by microwave radio waves. Although an experimental 40-mile 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. In the 1950s, large transcontinental microwave relay networks, consisting of chains of repeater stations linked by line-of-sight beams of microwaves were built in Europe and America to relay long distance telephone traffic and television programs between cities. Communication satellites which transferred data between ground stations by microwaves took over much long distance traffic in the 1960s. In recent years, there has been an explosive increase in use of the microwave spectrum by new telecommunication technologies such as wireless networks, direct-broadcast satellites which broadcast television and radio directly into consumers' homes. Microwaves are 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 the receiving antenna.
This allows nearby microwave equipment to use the same frequencies without interfering with each other, as lower frequency radio waves do. Another advantage is that the high frequency of microwaves gives the microwave band a large information-carrying capacity. A disadvantage is. Microwave radio transmission is used in point-to-point communication systems on the surface of the Earth, in satellite communications, in deep space radio communications. Other parts of the microwave radio band are used for radars, radio navigation systems, sensor systems, radio astronomy; the next higher part of the radio electromagnetic spectrum, where the frequencies are above 30 GHz and below 100 GHz, are called "millimeter waves" because their wavelengths are conveniently measured in millimeters, their wavelengths range from 10 mm down to 3.0 mm. Radio waves in this band are strongly attenuated by the Earthly atmosphere and particles contained in it during wet weather. In a wide band of frequencies around 60 GHz, the radio waves are attenuated by molecular oxygen in the atmosphere.
The electronic technologies needed in the millimeter wave band are much more difficult to utilize than those of the microwave band. Wireless transmission of informationOne-way and two-way telecommunication using communications satellite Terrestrial microwave relay links in telecommunications networks including backbone or backhaul carriers in cellular networksWireless transmission of powerProposed systems e.g. for connecting solar power collecting satellites to terrestrial power grids Microwave radio relay is a technology used in the 1950s and 1960s for transmitting signals, such as long-distance telephone calls and television programs between two terrestrial points on a narrow beam of microwaves. In microwave radio relay, microwaves are transmitted on a line of sight path between relay stations using directional antennas, forming a fixed radio connection between the two points; the requirement of a line of sight limits the separation between stations to the visual horizon, about 30 to 50 miles.
Before the widespread use of communications satellites, chains of microwave relay stations were used to transmit telecommunication signals over transcontinental distances. Beginning in 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 TD-2 and built by AT&T, connected New York and Boston in 1947 with a series of eight radio relay stations; these included long daisy-chained series of such links that traversed mountain ranges and spanned continents. Much of the transcontinental traffic is now carried by cheaper optical fibers and communication satellites, but microwave relay remains important for shorter distances; because the radio waves travel in narrow beams confined to a line-of-sight path from one antenna to the other, they don't interfere with other microwave equipment, so nearby microwave links can use the same frequencies. Antennas must be directional.
Typical types of antenna used in radio relay link installations are parabolic antennas, dielectric lens, horn-reflector antennas, which have a diameter of up to 4 meters. 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 the signal field cause unwanted attenuation. High mountain peak or ridge positions are ideal. Obstacles, the curvature of the Earth, the geography of the area and reception issues arising from the use of nearby land 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 the path must be ta
Claro Americas is part of América Móvil, a Mexican telecom group serving clients in Argentina, Chile, Costa Rica, the Dominican Republic, Ecuador, El Salvador, Honduras, Panama, Peru, Puerto Rico and Uruguay. The company's name means "bright", "clear" or "of course" in Spanish. Headquartered in Córdoba, Claro was launched in Argentina and Uruguay on March 25, 2008 in a rebranding of CTI Móvil; as of 31 March 2007 the former served more than 12.8 million subscribers on CDMA/1XRTT and GSM/GPRS/EDGE wireless. CTI Móvil purchased Hutchison Telecommunications Paraguay in July 2005 to begin serving customers in that country; as of 2006, Claro competed with international operators such as Tigo, Personal and VOX. In these countries, the company used slogans such as "Es simple. Es Claro." and "Claro es Internet móvil de alta velocidad." In Brazil, Claro was launched in 2003 with the merger of América Móvil-owned operators ATL, BCP, Tess Celular and Claro Digital. Claro expanded its service to the states of Bahia, Santa Catarina, Paraná and Minas Gerais.
As of 2012, the provider is available in over 2,000 Brazilian cities. With competitor Vivo, Claro was one of two operators to introduce the iPhone 3G in Brazil, with TIM participating later. Claro Brazil runs a pay-TV service, Claro TV. Slogans used by the Brazilian branch include "Nós escutamos" and "Escolha". While Claro has developed a large market share in Colombia, data for prepaid customers indicates that Claro has lost market share to competing providers Tigo and Movistar. Tigo and Movistar offer prepaid customers flat-rate per-minute plans for calls placed to all mobile service providers and landlines within Colombia; the cheapest per-minute rate for Claro prepaid customers is 249 pesos per minute, a rate valid for only nine "preferred Claro numbers". Per-minute rates increase for calls to Claro numbers not on a customer's "preferred" list and all calls to other cellphone providers or landline numbers. After the opening of telecommunications in Costa Rica when the monopoly of the ICE Group was dissolved, the government opened a tender for telecommunications companies wishing to enter Costa Rica.
Superintendencia de Telecomunicaciones of Costa Rica secured a license, the company began offering lines on November 5, 2011 to users who had registered on their website or through social networks. Service began on November 11. Claro Chile was known as Chilesat PCS, which renamed to Smartcom PCS. Claro was launched in Chile on August 6, 2006, after its acquisition of Smartcom PCS. Slogans such as "Yo soy Claro, y me gusta." have appeared in advertisements. In the mobile operator segment, Claro is third in market share behind Entel. Claro was launched in the Dominican Republic on January 31, 2007 after its acquisition of Verizon Dominicana on April 3, 2006, its Dominican Republic slogans have included "Claro que tienes más", "La Red donde todo es posible", "Estamos para ti". In Ecuador, America Movil was present with Conecel until February 2011; the name "Porta" was switched to "Claro" as part of America Movil's business strategy. It is the country's leading operator, with nearly nine million subscribers.
Claro was introduced in El Salvador and Nicaragua in September 2006. On November 16, 1996, the Guatemalan Congress passed the "Ley General de Telecomunicaciones", it was purchased by LUCA S. A. and Ricardo Bueso became Telgua's first President and CEO until 2000. In 2000, it joined America Movil and some time after it renamed the brands ALO and PCS Digital to Claro on Guatemala. Claro was introduced in Guatemala on September 7, 2006 as a rebranding of Telgua-owned PCS Digital and Alo de PCS; as of March 31, 2007 Claro in Guatemala had more than 5.2 million subscribers, with CDMA/1XRTT, GSM/GPRS/EDGE and UMTS/HSDPA wireless technology. Claro was introduced in Jamaica as a replacement for the MiPhone company. Oceanic Digital Jamaica Limited was a wholly owned subsidiary of América Móvil, providing service under the Claro name; the company built a GSM/UMTS/HSDPA network with the CDMA network, plans included fixed wireless and broadband service on the CDMA network. The Jamaican company was acquired by Digicel in late 2011, the network was closed in March 2012.
The Panama government licensed America Móvil to use spectrum in Panama under the Claro name. The government aims to expand competition and mobile access to the Panamanian population. Claro began operation on October 2005 after its acquisition of TIM Peru; the country has more than seventeen million customers. Claro was introduced in Puerto Rico on May 18, 20