1 Introduction 

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The cell phones have revolutionized the field of communications, redefining how we perceive voice communications. Traditionally,cellular phones remained out of reach of most consumers due to the high costs involved. As a result, service providers will invest time and resources to find new systems of higher capacity and thus lower cost. Cellular systems are benefiting from this research and have begun to develop as consumer products. 

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The cell phone is a telephone system completely wireless. During the course of this work, we will see, as the sounds are converted into electromagnetic signals that travel through the air, be received and transformed back into messages . In turn, shall be specified and compared the different technologies used in the process. What are the technologies currently used in wireless communications? What trends can be observed in terms of their development? 

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Initially, the phones were analog. An assessment of the reasons why there was a necessary migration of these systems to digital. 
The new revolution that implements the social use of cell generates both benefits and drawbacks. Accessibility to new media in a sharp increase in recent years, offers a constant contact between citizens. At this point the dilemma or the different interpretations of whether the new method of communication is positive or negative. 

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The massive increase in the use of cell in society has led us to think about the new behaviors that exist in people: we want to really know what the impact of mobile phones in people. In this way we generate various scenarios, questions that we will develop and respond to throughout the paper. It will point to the user interaction with the cell and through the same with society. If we consider only the utilitarian aspect of cellular Will people only used to make calls or additional features that have? Does having cell is a matter of habit, of necessity, or simply to be more fashionable? Have you created anaddiction to cellphones ? 

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Also see the effects that radiation can cause health effects. We’ll see what kind of diseases can cause. Is it true that cell phones cause cancer? What precautions should have if you own a mobile phone? 

2 History 
2.1 Background 
For the purpose of showing the evolution of the mobile phone in history will proceed to describe a brief overview that shows the progress of it: 
1843 – A talented chemist Michael Faraday began a deep study of the possible conduction of electricity in space. Faraday made its great advances in a technology of the last century that helped incalculably in the development of cellular telephony . 

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1947 – It was a great year for what the industry would be mobile .In that year they developed the ideas that allowed the use of mobilephones using “cells” to identify a user at any point where you make the call. However, the limited technology of the time forced to later developments. 

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1949 – In the era predecessor to cell phones , people who really needed communication mobile had to rely on the use of radio- phones in their cars. In the radio-telephone system, there was one central antenna per city, and a few channels available in the tower. 
This central antenna meant that the phone in the vehicle antenna would require a powerful, powerful enough to transmit 50 or 60 kms away. This also meant that not many people could still use the radio- phone s – simply were not enough channels to connect. 
This year in the U.S. authorized six additional mobile channels to radio common carriers, which defined as companies that do not provide landline telephone service public, but are interconnected to the public telephone network and provide wireless phone service equivalent. Then the number of channels increased from 6 to 11, reducing the width and band to 30 kHz. and the channel spacing between the old. 

1964 – To date, systems of mobile operating only in manual mode, an operator of mobile phone special handling each call, and from each unit mobile . In 1964, the automatic channel selector systems were put into service for the systems of mobile telephony . This eliminated the need for the operation press-to-Talk (push-to-talk) and allowed customers to dial calls directly, without the help of an operator. The MTS (Mobile Telephone System) uses radio channels FM to establish communication links between mobile phones and s transceivers central base station, which is related to the exchange of mobile local telephone lines using normal metal. MTS systems serve an area of approximately 60 km to the round and each channel operates similarly to a party line. Each channel can be assigned to multiple subscribers, but only a subscriber can use at once. If the pre-assigned channel is busy, the subscriber must wait until one becomes vacant, before making or answering a call. 

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1971 – The growing demand in the frequency spectrum of saturated mobile prompted to seek a way to provide efficiency higher frequency spectrum. This year, AT & T made a proposal on the technical feasibility of providing a response to the above. It began to outline the principle of cellular radio. 
“In this year in Finland was the first network launched successful public mobile telephone network called ARP. The network is seen as Generation 0 (0G), with just over proprietary networks and networks of local coverage. Details of the technology used at the time detailed in the next section. 

1973 – Dr. Martin Cooper is considered the inventor of the telephonehandset. Regarded as “the father of mobile telephony”, being general manager of systems of Motorola made a call to competitors of AT & T from their mobile phones, becoming the first person to do so. 

Martin Cooper with the Motorola DynaTAC 
1977 – The mobile phones will be made public s, beginning the tests on the market. The city of Chicago was the first to start with 2000 customers. Eventually, other lines of evidence appear in Washington DC and Baltimore. 
1979 – While Americans were pioneers in technology, the first commercial systems appeared in Tokyo, Japan by NTT in 1979. 
1983 – Chicago, Washington DC and Baltimore are the scenes of the first commercial launches of mobile systems in the United States. 

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1983 – The AMPS (Advanced Mobile Phone System) is launched using frequency bands from 800 MHz to 900 MHz and 30 kHz. of bandwidth for each channel as a fully automated telephone service.It is the first standard cell phone in the world. 
1986 – With this starting point, in several countries has spread themobile phone as an alternative to conventional wireless telephony.By 1986 mobile phone users reach 2 million in the U.S. alone. 
Because of this wide acceptance, the service began to fill up quickly, creating the need to develop and implement other forms of multiple access channel and transform the analog to digital in order to accommodate more users. 

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1987 – The industry reached 1000 million dollars in revenue. 
1988 – This year changed many of the typical technologies of the past. It creates a new standard, the TDMA Interim Standard 54, which is formalized in 1991. 
- Motorola introduces mobile phone DynaTAC, the first radiotelephone purely “mobile”. The phone , nicknamed “the brick”, had an hour of talk time and eight hours of standby time. 
1996 – Bell Atlantic Mobile launches first CDMA commercial network in the United States. 
1997 – Users of the wireless industry, cellular, PCS and ESMR-over 50 million. 
- Log in to use the digital network and wireless voice and data (2G) 
October 13, 2003 – 20th Anniversary of commercial wireless communications. 
Present in the United States, Latin America and Asia: 
 More than 182 million Americans are mobile phone users. 
 200.000 is the number of times a day in which someone calls for help from a mobile phone. 
 In Latin America, 37 of every hundred people are mobile phone subscribers. This determines some 190 million mobile phone users, against 88 million fixed telephony. 
 The growth of mobile telephony in the Caribbean between 1997 and 2003 was 25%, two times more than the growth of fixed telephony. 
 In terms of technology, in the region 73.3 million subscribers use the second generation (GSM), 2.2 million remain analog, the first in the market, and two million are using the pager system as a means of communication. 

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 The situation in Asia is quite different. Although the market penetration of mobile phones remains below 25%, most Asian markets saturate much earlier than the markets of Japan or Western Europe due to the relative low income. This is particularly true for China, India and Indonesia, which collectively make up over 70% of the inhabitants of the region. However, the average market penetration in these countries is only about 17%, and remain below 35% over the next 5 years. 

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April 3, 1973

Cooper, general manager of Motorola’s Communications Systems Division at the time, placed the first call to his rival, Dr. Joel S. Engel at AT&T’s Bell Labs. He publicly demonstrated the new technology in the streets of New York, using a “brick”-like 30-ounce phone. Martin said “As I walked down the street while talking on the phone, sophisticated New Yorkers gaped at the sight of someone actually moving around while making a phone call. Remember that in 1973, there weren’t cordless telephones, let alone cellular phones. I made numerous calls, including one where I crossed the street while talking to a New York radio reporter – probably one of the more dangerous things I have ever done in my life.”

It took 10 years to bring this new technology to market. Motorola introduced the 16-ounce DynaTAC phone into commercial service in 1983. The phone cost the consumer a paltry $3,500.

Cell Phones Today

Fast forward to today. Martin Cooper’s Star Trek-inspired vision has come to fruition. Today there are nearly 3 billion cell phone users world-wide. We use them everyday and they have seeped into every aspect of our lives, from checking email and texting to using GPS and taking pictures. And it all started 36 years ago today. It’s mind-boggling how much our world has changed in one generation’s time.

References:

• http://inventors.about.com/cs/inventorsalphabet/a/martin_cooper.htm
• http://en.wikipedia.org/wiki/Martin_Cooper_(inventor)
• http://en.wikipedia.org/wiki/Mobile_phone
• http://www.engadgetmobile.com/2007/09/05/planet-earth-now-home-to-four-billion-phone-lines/

Read more in this original July, 1973, Popular Science article.