Noise in measurements obtained by sampling

Simple signal processing tools are used to describe noise in sampled measurements. Particular attention is paid to aliasing and the modification of noise spectra by the sampling process. The principles discussed are applied to near-optimal measurements of DC and AC signals in noise, and to the measurement of noise power. Specific problems have been chosen to demonstrate novel approaches and to clarify situations where confusion has arisen. Examples include alternative definitions of equivalent noise bandwidth, the bandpass sampling theorem, quantization and dither, the variance in the mean of correlated measurements, the exploitation of anticorrelation in resonant transducers, the ideal averaging filter, the resolution of synchronous demodulators, and sampling demodulators.