Circuit noise reduction by analogue lowpass filtering and data averaging

All electrical signals are, to some extent, contaminated by noise. Two popular techniques for eliminating noise are analogue lowpass filtering and data averaging. Here, consideration is given to the cutoff frequency of analogue lowpass filters, and the minimum number of data samples needed to be averaged in order to reduce noise with known autocorrelation function within a predefined limit. The time delays introduced by both analogue lowpass filtering and data averaging are given. Finally, the signal-to-noise ratio, the averaging technique used in a capacitance/resistance spectroscopic tomography system design and their effect on measurement accuracy and data acquisition rate are analysed