Influence of Lower Cutoff Frequency on the Measured Variance of 1/f Noise

Previous experimental comparisons of 1/f and Nyquist noise in carbon resistors reveal that both are normally distributed in any time interval but that 1/f noise appears to have a nonstationary variance. The present paper examines the possibility that this fluctuation is caused by insufficient sampling of the 1/f noise signal. It is hypothesized that the 1/f noise is wide‐sense stationary and the number of independent samples per measurement is found and shown to be far less than that for Nyquist noise. An experiment is then described in which the number of samples is sufficiently large to eliminate this source of variance fluctuation. The results exhibit the same spread in measured 1/f noise variance reported earlier, suggesting that an intrinsic nonstationarity does exist in this noise process when produced in carbon resistors.