Transcript Introduction - Eastern Illinois University

School of Business
Eastern Illinois University
Additional questions about
Data & Signals
© Abdou Illia, Fall 2004
Data and signals
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What is the basic function of a modem?
To convert digital data into analog signals and back again.
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What is the basic function of a codec?
To convert analog data into digital signals and back again.
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Why are digital encoding techniques (like NRZ-L or
Differential Manchester) necessary?
Because digital data must be converted to digital signals for
proper transmission over a medium.
Data and signals
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What is the spectrum of a signal?
The range of frequencies that a signal spans from minimum to
maximum.
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How does baud rate differ from bits per second?
Baud rate is the number of clock cycles per second. The Bit rate, on
the other hand, is the number of bits per second. In each clock cycle
one or more bits could be sent The following formula shows the
relation between the two: Bit Rate = Baud Rate * Bits per clock cycle
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Why we need to use a translator when both device (or source of
data) and line are digital?
Usually the device and the line use different signaling formats
(different bit rate, different number of possible states, different voltage
level, etc.). So, a translator is needed to convert between the two
different formats.
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