by
Geo-Alexandru Spanulescu, Grade 8,
School no. 195, Bucharest
Assisting by Professor: Florentina Iofciu
Inventor: Martin Cooper
Dr Martin Cooper was the first person to successfully invent a mobile and make a call on one. He was born on 26 December 1928 in Chicago.
Martin Cooper pioneered Motorola’s research for cellular phones. He was raised in Chicago, and attended the Institute of Technology in Illinois where he obtained a degree in electrical engineering. After working for the navy he also worked for a telecommunications company, and got a job with Motorola in 1954. Cooper worked on the first portable handheld police radio.
The first cellular phones to be created were very large and bulky. This made them difficult to carry around. The first cell phone came to the market in 1984 from Motorola and weighed 2 pounds. It was a DynaTac 8000X which was selling for $3, 995. A few years later, in 1991, the Motorola MicroTac Lite was created which cost $1,000.
The structure of cellular phones has evolved. They have decreased drastically in size and weight. Currently the smallest cell phone in the world weighs slightly more than a pack of cigarettes and is 68 X 38.5 X 22 mm. Cell phones are now so small that they can be carried around more conveniently, but are very easy to loose. They come with numerous features and functions. There are different styles of cell phones such as a flip phone or the slide phone.
It is easy to customize a cell phone by choosing the model, color, style, its features and functions, and size. There are even phone covers that change the face design of the phone. Various accessories are available such as car chargers, belt clips, glowing antennas, and data cables.
Cell phones originated from the radio, and evolved into the telephone. Each city is divided up into cells that allow frequencies to be transferred. Each cell has a hexagonal shape with a tower in the center (base station), and a building that contains radio equipment.
Every carrier within a city uses the same central office, the Mobile Telephone Switching Office (MTSO). A cell phone carrier is usually allowed about 832 radio frequencies to use per city. With the analog system, one cell phone uses 2 frequencies per phone call, but each cell has about 56 voice channels available which means that 56 cell phones can be in use at one time. This all increases with digital systems and makes cellular phone work more efficiently.
When the cell phone is activated it searches for a System Identification Code (SID) on a control channel. A SID is a different 5 digit number that is assigned. The control channel is responsible for allowing the phone and base station to communicate about call set–up and channel changing. If a control channel can not be found then the phone is out of range and has “no service”. When the cell phone gets the SID, it is compared to the SID that has already been set in the phone and if they match then this means two cell phones of the same home system have been connected. Also, the cell phone gives off a registration request. The MTSO keeps a record of the phone’s location in order to know what cell it is in when in needs to ring. Once the phone rings and the cell has been determined, the MTSO chooses a frequency pair that the phone uses to take the call. Over the control channel the MTSO communicates with the cell phone to determine which frequencies to use. Then the cell phone and the tower switch with those frequencies and the call is connected. If the cell phone reaches the end of the cell the strength of the signal diminishes so the MTSO allows the 2 base stations to connect and get on a control channel to decide which frequency to switch to.
Cell phones have become a necessity for many people throughout the world. The ability to keep in touch with family, business associates, and access to email are only a few of the reasons for the increasing importance of cell phones. Today's technically advanced cell phones are capable of not only receiving and placing phone calls, but storing data, taking pictures, and can even be used as walkie talkies, to name just a few of the available options.
Cell phones are the perfect way to stay connected with others and provide the user with a sense of security. In the event of emergency, having a cell phone can allow help to reach you quickly and could possibly save lives. However, the importance of cell phones goes way beyond personal safety. Modern cell phones are capable of internet access, sending and receiving photos and files, and some cell phones are equipped with GPS technology, allowing for use in most locations around the world and allowing the cell phone to be found or the user located in the event of loss or emergency.
Cell phone reception has become reliable and of high quality due to advances in wireless technology. Wireless service providers offer excellent packages and promotions for cell phone users. Finding a dependable service provider is no longer an issue for cell phone users. The expansion of the wireless service provider industry gives cell phone users a choice and the increased competition has caused a drop in prices of wireless cell phone service. The importance of cell phones goes way beyond the ability to make or receive phone calls. Cell phone users can instantly send data to the home or office, check for important email, use their cell phone as a PDA or calendar, and store photos which can be easily transferred to a PC or laptop computer.
Cell phone manufacturers have produced a wide range of cell phones, which sell for prices that range from very inexpensive to over one thousand dollars. The available options give users the choice of purchasing a basic cell phone to use simply for making calls, or choosing a complex, technologically advanced cell phone that can perform as many or even more tasks that a home computer. Over the past decade, the increasing importance of cell phones has made them almost a necessity for most people. Even remote and underdeveloped countries have some access to cell phone technology and wireless services.
The importance of cell phones has increased the competition in the wireless service provider industry, making cell phones very affordable and very easy to use. Cell phones have become almost a status symbol in addition to the convenience and security that comes from owning them.
BIBLIOGRAPHY:
http://library.thinkquest.org/04oct/02001/original.htm
http://library.thinkquest.org/04oct/02001/present.htm
http://library.thinkquest.org/04oct/02001/work.htm
http://library.thinkquest.org/04oct/02001/inventors.htm
http://wiki.answers.com/Q/Who_is_Dr_Martin_Cooper
http://www.bharatbhasha.com/communication.php/19952
