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Noise in Baseband Analog Systems

Noise in Baseband Analog Systems. Analog and Digital Communications Autumn 2005-2006. LPF. Noise. White Noise Filtered/Colored Noise. Power in filtered noise increases with filter bandwidth. Noise Equivalent Bandwidth. Average power in filtered noise:. (Noise equivalent bandwidth).

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Noise in Baseband Analog Systems

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  1. Noise in Baseband Analog Systems Analog and Digital Communications Autumn 2005-2006 CS477: Analog and Digital Communications

  2. LPF Noise • White Noise • Filtered/Colored Noise Power in filtered noise increases with filter bandwidth CS477: Analog and Digital Communications

  3. Noise Equivalent Bandwidth Average power in filtered noise: (Noise equivalent bandwidth) CS477: Analog and Digital Communications

  4. Baseband Signals with Noise • Baseband Signals • Signals in which no carrier modulation is performed • Baseband performance is usually used as reference for comparison. We will use it! • Performance criteria for analog systems • Signal-to-noise ratio (SNR) • Performance criteria for digital systems • Bit error rate (BER) and transmission rate CS477: Analog and Digital Communications

  5. Additive Noise A baseband receiver Received Signal Linear Receiver (Subscript used for destination) (signal and noise uncorrelated) Additive Noise Receiver Model CS477: Analog and Digital Communications

  6. Baseband Noisy Receiver How to measure the destination SNR? 1. Turn off signal and measure the output 2. Turn on signal and measure the output 3. Take the ratio CS477: Analog and Digital Communications

  7. Additive Noise Loss LPF Fig: A baseband noisy transmission model (Destination noise power) Analog baseband noisy transmission (Upper bound on destination SNR) 1. Destination noise power is proportional to filter bandwidth 2. A wideband signal suffers more from noise contamination CS477: Analog and Digital Communications

  8. Additive Noise Loss LPF To next repeater is the power loss incurred in each section Improvement factor from no-repeater case: Use of Repeaters What if the destination SNR is below desired level? USE A REPEATER!!! CS477: Analog and Digital Communications

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