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Search for a Signal: The Role of Mathematical Codes in Fostering a Cell Phone Communication Revolution
Pages 1-4

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From page 1...
... Yet, Americans do something like this a billion times a day, every time they talk on their cell phones. Without realizing it, they are using mathematical codes, called error-correcting codes, to turn staticky radio signals into clear human speech.
From page 2...
... This means that they convert a spoken signal into a string of 1s and 0s and transmit them to the destination phone, which to denote a unit of converts the 1s and 0s back to an audio signal. Digital technology is based information (coded on the work Shannon did 35 years before cell phones arrived on the market.
From page 3...
... But in 1993, French engineers Claude Berrou and Alain Glavieux stunned the coding community with a new method called turbo codes that requires only 10 percent more power to transmit than the theoretical minimum. A turbo encoder uses two separate encoders -- one encoding the message directly, the other scrambling it first and then encoding.
From page 4...
... The LDPC decoder does this by assigning each bit a probability of being a "0" or "1" and updating the Error-correcting codes probability as more information is available. help keep cell phone conversations clear in Such complexity requires tremendous computing power.

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