How exactly this is the topic of modula8on signal

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Unformatted text preview: cy components (called Fourier analysis) weights of harmonic frequencies 24 12 10/6/13 Effect of Less Bandwidth •  Less bandwidth degrades signal (less rapid transi8ons) Lost! Bandwidth Lost! Lost! 25 25 Signals over a Wire •  What happens to a signal as it passes over a wire? –  The signal is delayed (propagates at ⅔c) –  The signal is aQenuated (goes for m to km) –  Noise is added to the signal (later, causes errors) –  Frequencies above a cutoff are highly aQenuated EE: Bandwidth = width of frequency band, measured in Hz CS: Bandwidth = informa8on carrying capacity, in bits/sec 26 13 10/6/13 Signals over a Wire (2) •  Example: 1: AQenua8on: Sent signal 2: Bandwidth: 3: Noise: 27 Signals over Fiber •  Light propagates with very low loss in three very wide frequency bands –  Use a carrier to send informa8on AQenua8on (dB/km By SVG: Sassospicco Raster: Alexwind, CC- BY- SA- 3.0, via Wikimedia Commons Wavelength (μm) 28 14 10/6/13 Signals over Wireless (§2.2) •  Signals transmiQed on a carrier frequency •  Travel at speed of light, spread out and aQenuate faster than 1/dist2 •  Mul8ple signals on the same frequency interfere at a receiver •  Other effects are highly frequency dependent, e.g., mul8path at microwave frequencies 29 Wireless Mul8path •  Signals bounce off objects and take mul8ple paths –  Some frequencies aQenuated at receiver, varies with loca8on –  Messes up signal; handled with sophis8cated methods (§2.5.3) 30 15 10/6/13 Introduc8on to Computer Networks Modula8on (§2.5) Compu...
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This document was uploaded on 04/04/2014.

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