ch7_snr - EEN 404 Communication Systems Ch7 Noise in...

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1 EEN 404 EEN 404 Communication Systems Communication Systems Ch7 Noise in Modulation Systems Ch7 Noise in Modulation Systems
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2 Signal-to-noise ratio (SNR) is a figure of merit to evaluate system performance SNR := signal power noise power Noise in modulation systems SNR in Decibel (dB) = 10 log 10 SNR DSB modulation, SNR = 0dB 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -1 -0.5 0 0.5 1 Amplitude Original signal 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -2 -1 0 1 2 Modulated signal, fc=100kHz 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -1 -0.5 0 0.5 1 Time (second) Demodulated signal 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -1 -0.5 0 0.5 1 Original signal 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -2 -1 0 1 2 Modulated signal, fc=100kHz 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -1 -0.5 0 0.5 1 Time (second) Demodulated signal DSB modulation, SNR = 10dB
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3 Baseband systems: no modulation and demodulation Input signal spectrum and noise PSD noise power: signal power: (SNR) i (SNR) o
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4 Output signal spectrum and noise PSD noise power: signal power: Filter enhances the SNR by:
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This note was uploaded on 10/28/2010 for the course EEN 404 taught by Professor X.cai during the Spring '10 term at University of Miami.

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ch7_snr - EEN 404 Communication Systems Ch7 Noise in...

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