ece4305_L05

ece4305_L05 - Noise ECE4305: Software-Defined Radio Systems...

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Unformatted text preview: Noise ECE4305: Software-Defined Radio Systems and Analysis Professor Alexander M. Wyglinski Department of Electrical and Computer Engineering Worcester Polytechnic Institute Lecture 5 Professor Alexander M. Wyglinski ECE4305: Software-Defined Radio Systems and Analysis Noise Theoretical Foundations Additive White Gaussian Noise Narrowband Noise Definition I Noise is an unwanted signal that is superimposed on top of a useful information signal I Introduction of noise to useful information signal usually occurs prior to interception and decoding by receiver I Noise can be modeled as a random variable I Different noise-generating phenomena can be modeled by different random variables I Although noise signal not known precisely, its statistical characteristics can be used in the communication system design process Professor Alexander M. Wyglinski ECE4305: Software-Defined Radio Systems and Analysis Noise Theoretical Foundations Additive White Gaussian Noise Narrowband Noise Noise Sources I Noise originates from multiple sources within the communication system transmission environment I Natural sources I Solar flare activity and atmospheric conditions, e.g., ionosphere I Johnson-Nyquist noise, i.e., thermal noise in conductive materials I Lightning I Cosmic background noise I Human-built sources I Microwave ovens (2.4 GHz) I Power transmission lines (60 Hz) I Other wireless transmissions Professor Alexander M. Wyglinski ECE4305: Software-Defined Radio Systems and Analysis Noise Theoretical Foundations Additive White Gaussian Noise Narrowband Noise Noise Blurs Intercepted Signals I Randomness of noise makes detection and decoding of useful signals difficult 50 100 150-0.5 0.5 1 1.5 time [seconds] amplitude [volts] Figure: Signal Before Noise is Added. Notice Clear Pulse Shapes of Signal. 50 100 150-0.5 0.5 1 1.5 time [seconds] amplitude [volts] Figure: Signal After Noise is Added....
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This note was uploaded on 01/13/2011 for the course ECE 4305 taught by Professor Wy during the Spring '10 term at WPI.

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ece4305_L05 - Noise ECE4305: Software-Defined Radio Systems...

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