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Unformatted text preview: ME365 Noise and Noise Rejection 1 Noise Sources Characterizing Noise Signal-to-Noise Ratio (SNR, S/N) Power Spectral Density Modes of Interference Noise Rejection: Filtering Modulation Shielding & Grounding Differential Amplifier Averaging Noise & Noise Rejection ME365 Noise and Noise Rejection 2 Noise Noise is any unsteady component of the measurement signal that causes the instantaneous value of the signal to differ from the instruments rendition of the true value. Time x ( t ) ME365 Noise and Noise Rejection 3 Noise Sources Internal Temperature-induced random noise in conductors (Johnson noise) Random current fluctuations in transistors (Shot noise) Flicker noise External AC Interference Communication Interference Switching Interference Mechanical/Structural Vibration ME365 Noise and Noise Rejection 4 Average Signal Power Average power (in Watts) dissipated when voltage signal is connected to a 1 resistor: Assume the actual signal s ( t ) and the noise n ( t ) are independent of one another: Root Mean Square (RMS) voltage of a signal is:...
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- Fall '07