April 27, 2008
The inner workings of a cell phone may be a little difficult to understand since it is a highly sophisticated device, notwithstanding the fact that it is a very common gadget used by people in general. One of its aspects that is worth understanding is with regards to its frequency. This can be better understood by comparing a cell phone to a CB radio or a walkie-talkie.
Both the CB radio and walkie-talkie are half-duplex devices wherein two people communicating use the same frequency which means only one person can talk at a time. A cell phone is a full-duplex device which allows for one frequency to be used for talking and another separate frequency for listening, which means that both people can talk at once. A typical cell phone can communicate on 1,664 channels or more as compared to a walkie-talkie which has one and a CB radio that has 40 channels. Since cell phones operate within cells, they are given incredible range to hundreds of miles while a walkie-talkie can transmit about 1 mile and about 5 miles for the CB.
April 25, 2008
Cell phones are equipped with more and more features which are bound to be the basis in choosing what to purchase. Features would more or less fall into five basic categories: physical, fun, productivity, network technology and accessibility.
Physical characteristics consist of the design, size and weight, battery, antenna and display. Fun features would include camera, music, messaging, gaming, ring tones and video. Productivity features are made up of calling, phone book, PDA, connectivity, push-to-talk, data/Internet, download speed/technology, operating system and memory. Network technology is concerned about interface, bands and modes. Accessibility features may include hearing and compatibility, keypad buttons and display font size. Having all features is not necessarily the wise choice but knowing the options would more or less help the user assess his/her personal requirements of a cell phone.
A cellular phone is a product of the combination of two great technologies: telephone and wireless communication. It should be noted that a cell phone is actually a radio or at least an extremely sophisticated radio. Before cell phones came to be, mobile communication abilities were usually provided by radio telephones installed in cars. There was one central antenna tower per city with about 25 channels available on such tower for the radio telephone system. However, there were not so many people that could use radio telephones due to the limited channels and the need for a very powerful transmitter just to transmit 40 or 50 miles away.
The genius of the cellular system lies in the division of a city into small cells which allowed for extensive frequency reuse across the area. This facilitated the simultaneous use of millions of people of their cell phones. Its amazing how inventions of the 1800s can still continue to produce better options as time goes by.