BDC5eChapter16 - Chapter 16: Data Communication...

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Chapter 16: Data Communication Fundamentals Business Data Communications, 5e
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Business Data Communications, 5e 2 Data Communication Components Data Analog: Continuous value data (sound, light, temperature) Digital: Discrete value (text, integers, symbols) Signal Analog: Continuously varying electromagnetic wave Digital: Series of voltage pulses (square wave) Transmission Analog: Works the same for analog or digital signals Digital: Used only with digital signals
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Business Data Communications, 5e 3 Analog Data Signal Options Analog data to analog signal Inexpensive, easy conversion (eg telephone) Data may be shifted to a different part of the available spectrum (multiplexing) Used in traditional analog telephony Analog data to digital signal Requires a codec (encoder/decoder) Allows use of digital telephony, voice mail
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Business Data Communications, 5e 4 Digital Data Signal Options Digital data to analog signal Requires modem ( mo dulator/ dem odulator) Allows use of PSTN to send data Necessary when analog transmission is used Digital data to digital signal Requires CSU/DSU (channel service unit/data service unit) Less expensive when large amounts of data are involved More reliable because no conversion is involved
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Business Data Communications, 5e 5 Transmission Choices Analog transmission only transmits analog signals, without regard for data content attenuation overcome with amplifiers signal is not evaluated or regenerated Digital transmission transmits analog or digital signals uses repeaters rather than amplifiers switching equipment evaluates and regenerates signal
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Business Data Communications, 5e 6 Data Signal Transmission System A D D D A A Data, Signal, and Transmission Matrix
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Business Data Communications, 5e 7 Advantages of Digital Transmission The signal is exact Signals can be checked for errors Noise/interference are easily filtered out A variety of services can be offered over one line Higher bandwidth is possible with data compression
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Business Data Communications, 5e 8 Why Use Analog Transmission? Already in place Significantly less expensive Lower attenuation rates Fully sufficient for transmission of voice signals
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Business Data Communications, 5e 9 Analog Encoding of Digital Data Data encoding and decoding technique to represent data using the properties of analog waves Modulation: the conversion of digital signals to analog form Demodulation: the conversion of analog data signals back to digital form
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Business Data Communications, 5e 10 Modem An acronym for modulator-demodulator Uses a constant-frequency signal known as a carrier signal Converts a series of binary voltage pulses into an analog signal by modulating the carrier signal The receiving modem translates the analog signal back into digital data
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This note was uploaded on 04/27/2010 for the course BAMU BSC taught by Professor Kmm during the Spring '10 term at University of New York in Prague.

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BDC5eChapter16 - Chapter 16: Data Communication...

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