lec16 - ENGR 111 Lecture 16 Reading: Chapters 23,24 Class...

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ENGR 111 Lecture 16 Reading: Chapters 23,24 Class notes
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Review of last lecture z Signals attenuate or degrade over distance z Noise degrades signal quality z Signal to Noise ratio determines how much information can be transmitted (Shannon) z Given an analog signal (such as audio), digitization requires > 2*W samples/sec, where W = signal frequency bandwidth (Nyquist) z Digital transmission is controlled by these two theorems
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Is everything digital? z No, almost everything in the physical world is analog { My voice during the lecture (pitch, loudness) { The images on the screen (brightness, color) z Analog -- Continuous signal that can take any value { Not restricted to 0s and 1s z Digital is easier for storage, transmission
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Analog -- Digital z Humans perceive everything in analog z Machines like digital -- What to do? z Convert analog signals to digital for machines, transmission z At the other end, convert digital to analog for humans z A-D, D-A conversion z Digital Signal Processing deals with this
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Generic Transmission system
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AM Radio transmission
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Spectrum
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Spectrum z Limited resource z Needs to be used as efficiently as possible z Split into multiple bands for multiple applications z Within each band, share frequency to allow multiple parties to operate z EM Theory deals with spectrum properties
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Where are the digital transmissions?
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This note was uploaded on 03/26/2008 for the course ENGR 111 taught by Professor Walker during the Fall '07 term at Texas A&M.

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lec16 - ENGR 111 Lecture 16 Reading: Chapters 23,24 Class...

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