Cell phone (telefone celular) is a wireless, portable, long-range, electronic telephone, which during voyage can seamlessly change antenna connections, from one radio reception cell to someone else radio reception cell, without dropping or losing the ongoing call.
Besides the accepted voice function of a telephone, most recent cell phones (telefone celular) have features such as Sms for text messages, Mms for multimedia messages, radio, games, internet connectivity for email, browsing, blogging, music (Mp3) playback, memo recording, built-in cameras and camcorders, ringtones, personal organizers, Push-to-Talk (Ptt), Bluetooth and infrared connectivity, call registers, streaming video, downloading video, video call, and also serve as wireless modems for Pcs that can be connected to the Internet.
The power in a cell phone (telefone celular) is obtained from rechargeable batteries, which can be recharged from the mains, a Usb port or a cigarette lighter port in an automobile. Nickel Metal Hydride were the most common types of batteries, which due to the "memory effect" (the user can recharge only when the entire battery is drained off) were supplanted by Lithium-Ion batteries, which did not suffer from any memory effect.
Cell phones (telefone celular) came into existence because of the invention of hexagonal cells in 1947, for the base stations by Bell Labs engineers at At&T. This was further advanced during the 1960s by Bell Labs. during a call, the channel frequency could not be changed automatically from one cell (base middle point coverage area) to someone else cell (base middle point coverage area) as the person traveled from the area of one cell to the area of someone else cell. Amos Joel of Bell Labs invented a breakthrough invention and called it as the `call handoff` by which the channel frequency could be changed automatically from one cell to someone else cell, during the same call, as the movable user traveled from one cell to someone else cell. Due to their heavy construction, these phones were used generally in automobiles.
The first practical cell phone in a non-vehicle setting, and which could be handheld, was invented by Martin Cooper, the normal boss (Communications Division) of Motorola, who made the world`s first handheld cell phone (telefone celular) call on April 3, 1973.
The technology by which the cell phone (telefone celular) works depends on the movable phone operator; however, all of them use electromagnetic radio waves, which are in touch with a cell site (base station). The base middle point is composed of some antennas which are mounted on a pole, tower, or building. Cell sites are spread at a length of 5 to 8 miles (approx. 8 to 13 km) from each other. The low power transceiver from the cell phone transmits the voice and data to the nearest cell site. during movement, the cell phone will "handoff" the information to other cell site. movable phone operators use many technologies to assert the smooth stream of digitized data from the cell phone to the cell site and vice versa.
The wireless telephone technologies are grouped under heads known as generations, starting from zero generation or 0G. The current generation going on is 4G; however, there are old cell phones (telefone celular) that still control on 1G, 2G, and 3G technologies. The wireless telephone technologies used in each generation are as given below:
0G: Ptt, Mts, Imts, Amts, Olt, Mtd, Autotel/Palm, Arp
1G: Nmt, Amps/Tacs/Etacs, Hicap, Cdpd, Mobitex, DataTac
2G: Gsm, iDen, D-Amps, Is-95/cdmaOne, Pdc, Csd, Phs, Gprs, Hscsd, WiDen, Cdma2000 1xRtt/Is-2000, Edge (Egprs)
3G: W-Cdma, Umts (3Gsm), Foma, Td-Cdma/Umts-Tdd, 1xEv-Do/Is-856, Td-Scdma, Gan (Uma), Hspa, Hsdpa, Hsupa, Hspa+, Hsopa
4G : Umb, Umts revising 8 (Lte), WiMax
Frequency bands: Smr, Cellular, Pcs
The impact of cell phone (telefone celular) usage on human condition has been of necessary worldwide concern. Explore studies in Copenhagen, from the Danish institute of Cancer Epidemiology, the National Cancer Institute, and the institute of Cancer Research, do not institute any link between cancer and cell phone usage. However, an intergovernmental group Iarc (International group for Explore on Cancer) forming part of the World condition organization of the United Nations, undertook a study of 4,500 users and found a statistically necessary link between cell phone usage and tumor frequency. further Explore is going on.
Cell phone (telefone celular) usage and driving is a common worldwide phenomenon. Some jurisdictions have banned usage of hand-held phones during driving, but allowed the hands-free fashion of cell phone usage while driving. However, studies have found out that the distraction is caused by the conversation itself; hence, both hand-held and hands-free cell phones lead towards road traffic accidents. further studies on cell phone usage and driving are going on.
Nokia Corporation is currently the world`s largest builder of cell phones (telefone celular). Other illustrious cell phone manufacturers, in alphabetical order, are 3G, Audiovox (now Ut Starcom), Benefon, BenQ-Siemens, Fujitsu, High Tech Computer Corporation (Htc), Kyocera, Lg Mobile, Motorola, Nec, Panasonic (Matsushita Electric), Pantech Curitel, Philips, Explore In Motion, Sagem, Samsung, Sanyo, Sharp, Siemens, Sierra Wireless, Sk Teletech, Sony Ericsson, T&A Alcatel, Toshiba, and Verizon.
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