Analog and Digital Signals, Time and Frequency ...

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Analog and Digital Signals, Time and Frequency

Representation of Signals

Required reading: Garcia 3.1, 3.2

CSE 3213, Fall 2010 Instructor: N. Vlajic

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? Data vs. Signal ? Analog vs. Digital ? Analog Signals

Simple Analog Signals Composite Analog Signals

? Digital Signals

Data vs. Signal

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Data ? information formatted in human/machine readable form

? examples: voice, music, image, file

Signal ? electric or electromagnetic representation of data

? transmission media work by conducting energy along a physical path; thus, to be transmitted, data must be turned into energy in the form of electro-magnetic signals

Transmission ? communication of data through propagation and

processing of signals

Idea, Feeling, Knowledge

Data

Coding

Sender

Signal

Decoding Signal

Channel or Communication Medium

Data Receiver

Signal Representation

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Signal Representation ? typically in 2D space, as a function of

time, space or frequency

? when horizontal axis is time, graph displays the value of a signal at one particular point in space as a function of time

? when horizontal axis is space, graph displays the value of a signal at one particular point in time as a function of space

time

space

The time- and space- representation of a signal often resemble each other, though the signal envelope in the space-representation is different (signal attenuates over distance).

Signal Representation (cont.)

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Example [ signal in time and space ]



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