An automatic characterization of a Gaussian noise source for undergraduate electronics laboratory

This paper describes a technique which allows the probability density and the probability distribution functions of a Gaussian noise source to be obtained in a very simple, low cost way. First a high-level noise source is described and the characterization of this source is done using only standard parts available at low cost and an easy-to-make test set. Probability density and distribution functions are measured using a synchronous modulation-demodulation technique and recorded by means of a digital storage oscilloscope connected to a compatible PC. This laboratory experiment is used by undergraduate students (of French IUT) with limited knowledge in electronics and mathematics to compare theoretical properties on noise probability with practical measurements. In this laboratory they have to analyze the technique used to measure probability density and distribution functions and to identify the Gaussian noise source in terms of mean value and variance. Finally they have to compare these quantities to those obtained by direct measurements with a “true RMS” voltmeter