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Bandpass Noise. Analog and Digital Communications Autumn 2005-2006. Additive Noise. CW modulated signal at receiver front end. Detector. BPF . is additive white gaussian noise (AWGN). (also a bandpass signal!). LPF . CW Analog Systems.
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Bandpass Noise Analog and Digital Communications Autumn 2005-2006 CS477: Analog and Digital Communications
Additive Noise CW modulated signal at receiver front end Detector BPF is additive white gaussian noise (AWGN) (also a bandpass signal!) LPF CW Analog Systems Most analog continuous-wave systems are bandpass systems and suffer from bandpass noise CS477: Analog and Digital Communications
What is is bandpass noise DSB: USSB: LSSB: Bandpass Noise It is colored and has finite power First deal with noise only. Turn the signal OFF… Let the bandpass filter for positive frequencies is: CS477: Analog and Digital Communications
is predetection noise is predetection noise power is transmission bandwidth, not the message BW Bandpass Noise Predetection Bandpass noise spectrum High transmission bandwidth means more predetection noise CS477: Analog and Digital Communications
Predetection SNR is an upper bound on SNR because Predetection SNR For baseband transmission, we defined: Therefore, for passband transmission: CS477: Analog and Digital Communications
is predetection bandpass noise has noise eq. BW equal to transmission BW are jointly stationary and gaussian Quadrature decomposition of Noise Properties of quadrature components (prove at home!): What are the spectral properties of quadrature components? Note: quadrature components are lowpass signals! CS477: Analog and Digital Communications
Type of modulation dictates PSD of Quadrature Components (prove it at home: see page 405 and example 9.2-3) Noise power can be easily computed for all types of Modulation because: CS477: Analog and Digital Communications
is Rayleigh distributed is Uniform Noise: Envelope and Phase (power in noise envelope) (complementary cdf) CS477: Analog and Digital Communications