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Amy B.'s List: 2Amy Engineering Research

    • Another technological triumph is the cell phone, a radio-linked device that is taking the world by storm. Old-style mobile telephones received their signals from a single powerful transmitter that covered an area about 50 miles in diameter, an interference-prone method that provided enough channels to connect only a couple of dozen customers at a time. Cellular technology, by contrast, uses low-powered base stations that serve "cells" just a few square miles in area. As a customer moves from one cell to another, the phone switches from a weakening signal to a stronger one on a different frequency, thus maintaining a clear connection. Because transmissions are low powered, frequencies can be reused in nonadjacent cells, accommodating thousands of callers in the same general area. 

      Although the principles of cellular telephony were worked out at Bell Labs in the 1940s, building such systems had to await the arrival of integrated circuits and other microelectronic components in the 1970s. In the United States, hundreds of companies saw the promise of the business, but government regulators were very slow in making a sufficiently broad band of frequencies available, delaying deployment considerably. As a result, Japan and the Scandinavian countries created the first cellular systems and have remained leaders in the technology. At the start there was plenty of room for improvement. Early cell phones were mainly installed in cars; handheld versions were as big as a brick, cost over a thousand dollars, and had a battery life measured in minutes. But in the 1990s the magic of the microchip drove prices down, shrank the phones to pocket size, reduced their energy needs, and packed them with computational powers. 

    •       1973       First portable cell phone call is made
       
           
      The first portable cell phone call is made by Martin Cooper of Motorola to his research rival at Bell Labs, Joel Engel. Although mobile phones had been used in cars since the mid-1940s, Cooper’s was the first one invented for truly portable use. He and his team are awarded a patent in 1975.
       
                 1975       U.S. military begins using fiber optics
       
           
      The U.S. military begins using fiber optics to improve communications systems when the navy installs a fiber-optic telephone link on the USS Little Rock. Used to transmit data modulated into light waves, the specially designed bundles of transparent glass fibers are thinner and lighter than metal cables, have greater bandwidth, and can transmit data digitally while being less susceptible to interference. The first commercial applications come in 1977 when AT&T and GTE install fiber-optic telephone systems in Chicago and Boston. By 1988 and 1989, fiber-optic cables are carrying telephone calls across the Atlantic and Pacific Oceans.
       
                 1976       Common channel interoffice signaling
       
           
      AT&T introduces common channel interoffice signaling, a protocol that allows software-controlled, networked computers or switches to communicate with each other using a band other than those used for voice traffic. Basically a dedicated trunk, the network separates signaling functions from the voice path, checks the continuity of the circuit, and then relays the information.
       
                 1978       Public tests of a new cellular phone system
       
           
      Public tests of a new cellular phone system begin in Chicago, with more than 2,000 trial customers and mobile phone sets. The system, constructed by AT&T and Bell Labs, includes a group of small, low-powered transmission towers, each covering an area a few miles in radius. That test is followed by a 1981 trial in the Washington-Baltimore area by Motorola and the American Radio Telephone Service. The Federal Communications Commission officially approves commercial cellular phone service in 1982, and by the late 1980s commercial service is available in most of the United States.
       
                 1990s (Mid)       Voice Over Internet Protocols
       
           
      The advent of Voice Over Internet Protocols (VoIP)—methods of allowing people to make voice calls over the Internet on packet-switched routes— starts to gain ground as PC users find they can lower the cost of their long-distance calls. VoIP technology is also useful as a platform that enables voice interactions on devices such as PCs, mobile handhelds, and other devices where voice communication is an important feature.
       
                 2000       100 million cellular telephone subscribers
       
         
      The number of cellular telephone subscribers in the United States grows to 100 million, from 25,000 in 1984. Similar growth occurs in other countries as well, and as phones shrink to the size of a deck of cards, an increasingly mobile society uses them not only for calling but also to access the Internet, organize schedules, take photographs, and record moving images.
    • The history of cell phones embarks on from the early days of 1920s – a period during which radios were emerging as effective communication devices. The very first usage of radio phones were in taxi/cars using two-way radio communication. Like any other electronic equipment, cell phones evolved over time, and each stage or era was most certainly interesting.
    • first public telephone call placed on a portable cellular phone
    • April 3, 1973

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