Most of the new digital cell phones have some sort of entertainment programing on them, ranging from simple dice-throwing games to memory and logic puzzles.
About 22% of American teenagers (more girls than boys) own a cell phone and it is now possible to locate a person using a cellular phone down to a range of a few meters anywhere in the world!
The GSM standard for digital cell phones was established in Europe in the mid-1980's; long before digital cell phones became common place in America. Cell phones are more popular in Europe than they in the United States with more than 60 percent of Europeans owning a cell phone; compared to about 40 percent of Americans owning a cell phone.
Facts for Cell Phone:
One of the most interesting features of a cell phone is it is really a radio -- a very sophisticated radio, but a radio nonetheless. Wireless communications can trace its roots to the invention of a radio by Nikolai Tesla in the 1880's. Alexander Bell - Meets Tesla and it was only a matter of time before these two technologies would merge.
In the days before cell phones, people who needed mobile-communication ability installed radio telephones in their cars. In the radio-telephone system, there was one central antenna tower per city, and perhaps 25 channels available on that tower. This central antenna meant that the phone in your car needed a very powerful transmitter; one big enough to transmit 40 or 50 miles (about 70 km). It also meant that not many people could use them as there just were just not enough channels to go around. (Rem,mber the ol' *party line*?)
The genius of the cell system is the division of a city into small cells (ergo the name) that allows extensive frequency reuse across a city so that millions of people can use cell phones at the same time. In the typical analog cell phone system of the USA, the cell phone carrier receives about 800 frequencies to use across a city. The carrier chops up the city into cells. Each cell is typically sized at about 10 square miles (26 square kilometers).
A single cell in an analog system uses one-seventh of the available duplex voice channels. That is, each cell (of the seven on a hexagonal grid) is using one-seventh of the available channels so it has a unique set of frequencies and there are no collisions: In other words, in any cell, many people can all be talking on their cell phone at the same time. With digital transmission methods, the number of available channels increases. Some digital systems can carry three times as many calls as an analog system can, so each cell has about 168 channels available at one time.
If you take a cell phone apart, you find that it contains just a few individual parts: A circuit board (which contains the "brains" of the phone) An antenna A liquid crystal display or more commonly called a (LCD) A keyboard A microphone A speaker A battery
Problem with Cell Phones:
Generally, non-repairable internal corrosion of parts results if you get the phone wet or use wet hands to push the buttons. If the phone does get wet, be sure it is totally dry before you switch it on so you can try to avoid damaging internal parts. (Use a hair-dryer or bathroom hand dryer.) Extreme heat in a car can damage the battery or the cellphones electronics. Extreme cold may cause a momentary loss of the screen display. Analog cell phones suffer from a problem known as "cloning." A phone is "cloned" when someone steals its ID numbers and is then able to make fraudulent calls on the owner's account.
Here is how cloning occurs: When your phone makes a call, it transmits the ESN and MIN to the network at the beginning of the call. The MIN/ESN pair is a unique tag for your phone -- this is how the phone company knows who to bill for the call. When your phone transmits its MIN/ESN pair, it is possible for nefarious sorts to listen (with a scanner ) and capture the pair. With the right equipment, it is fairly easy to modify another phone so that it contains your MIN/ESN pair, which allows the nefarious sort to make calls on your account
No comments:
Post a Comment