Cell phone (telefone celular) is a wireless, portable, long-range, electronic telephone, which during travel can seamlessly change antenna connections, from one radio reception cell to another radio reception cell, without dropping or losing the ongoing call.
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Besides the standard voice function of a telephone, latest 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.
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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 replaced 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 developed during the 1960s by Bell Labs. During a call, the channel frequency could not be changed automatically from one cell (base station coverage area) to another cell (base station coverage area) as the person traveled from the area of one cell to the area of another 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 another cell, during the same call, as the mobile user traveled from one cell to another cell. Due to their heavy construction, these phones were used mainly in automobiles.
The first practical cell phone in a non-vehicle setting, and which could be handheld, was invented by Martin Cooper, the General Manager (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 mobile phone operator; however, all of them use electromagnetic radio waves, which are in touch with a cell site (base station). The base station is composed of several antennas which are mounted on a pole, tower, or building. Cell sites are spread at a distance 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. Mobile phone operators use many technologies to maintain 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 operate 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 Revision 8 (LTE), WiMAX
Frequency bands: SMR, Cellular, PCS
The impact of cell phone (telefone celular) usage on human health has been of considerable worldwide concern. Research studies in Copenhagen, from the Danish Institute of Cancer Epidemiology, the National Cancer Institute, and the Institute of Cancer Research, do not establish any link between cancer and cell phone usage. However, an intergovernmental agency IARC (International Agency for Research on Cancer) forming part of the World Health Organization of the United Nations, undertook a study of 4,500 users and found a statistically significant link between cell phone usage and tumor frequency. Further research 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 contribute towards road traffic accidents. Further studies on cell phone usage and driving are going on.
Nokia Corporation is currently the world`s largest manufacturer of cell phones (telefone celular). Other notable 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, Research In Motion, Sagem, Samsung, Sanyo, Sharp, Siemens, Sierra Wireless, SK Teletech, Sony Ericsson, T&A Alcatel, Toshiba, and Verizon.
This article is under GNU FDL license and can be distributed without any previous authorization from the author. However the author's name and all the URLs (links) mentioned in the article and biography must be kept.
Interesting Facts About Cell Phones
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Christmas Sales Panasonic DMP-BD75 Ultra-Fast Booting Blu-ray Disc Player 201
Dec 30, 2011 08:36:17
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Panasonic DMP-BD75 Ultra-Fast Booting Blu-Ray Disc Player
Christmas Sales Panasonic DMP-BD75 Ultra-Fast Booting Blu-ray Disc Player Specifications
Internet-Ready Television
Internet-ready TVs use your broadband connection to deliver dynamic content, whether it's streaming video from Netflix, new music from Pandora, or a quick glance at today's weather forecast.
Although there is overlap, each manufacturer offers a unique bundle of free or paid services, including streaming video and music, social networking apps, online photo galleries, news and financial updates, weather info, sports scores, and a variety of other smartphone-like applications.
Manufacturers continue to add new content to their offerings, keeping customers current through firmware updates, and making a bit of research a prudent step in your buying decision.
Learn more about Internet TVs, how they work, what services are offered by different manufacturers, and exactly what you'll need to get started at our Internet TV 101 customer center.
(March 2011)
Experience original movie quality with the DMP-BD75 Blu-ray Disc Player.
New Stylish Interface
A stylish and simple menu design is achieved by using large menu icons and illustrations. Operation is also easier for the Blu-ray disc player, which features a simple menu, thanks to its one-click action, you simply place the remote control cursor onto the menu item that you want to choose, and the menu proceeds smoothly to the next screen. It's easy, even for first-time users.
NETFLIX, CINEMANOW, VUDU Compatible
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Ultra Fast Booting Blu-ray Disc Player
After starting the player, the time it takes from launching the menu to playing a disc is much shorter than in conventional models. Starting and loading the disc from standby is also quick, for more comfortable movie viewing.
Select Specifications
Supported Formats | |
---|---|
BD-ROM Playback: | BD-Video |
BD-RE / BD-RE DL: | Version 3, JPEG |
BD-R/BD-R DL: | Version 2, MKV |
DVD Playback: | DVD Video |
DVD-R/-RW/-R(DL) Playback: | DVD Video, DVD-VR, AVCHD, MP3/JPEG (DVD-R/ DVD-R DL,) MKV (DVD-R/ DVD-R DL) |
+R/+R(DL)/+RW Playback: | Video, AVCHD |
CD-R/-RW: | CD-DA, MP3, JPEG, MKV |
USB: | JPEG, MP3, MKV |
LAN (Ethernet) Terminal : | Yes (for BD-Live and Firmware Update) |
Input/Output | |
HDMI (Output): | 1 |
USB Port: | 1 (Front) |
Video Out: | Yes |
Analog Audio Out: | 2ch |
SD Memory Card Slot: | No |
Ethernet: | Yes (for BD-Live and Firmware Update) |
Weight and Dimensions | |
Dimensions (WxHxD): | 16-15/16" x 1-7/16" x 7-1/16" |
What's in the Box
Panasonic DMP-BD75, Remote Control With Two AA Batteries, User's Manual
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