Low-Frequency Variance Noise

Abstract

Variance fluctuations in 1/f noise examined with apparatus capable of responding to zero frequency signals are found to have the same magnitude as those in band-limited 1/f noise signals. The distribution of variances in identical sample lengths is skewed to small values in the case of current noise in a carbon resistor and is symmetrical in the case of current noise in a germanium p-n junction. The probability amplitude is normally distributed in all samples investigated, from 10 to 2400 sec long. Both the average variance and the variance of the variance are found to increase as the logarithm of the sample duration.