Estimating EMC measurement uncertainty using logarithmic terms (dB)

This paper gives background for understanding the use of logarithmic data for making statistical calculations to estimate measurement uncertainties in EMC measurements. When multiplicative data are used, the lognormal distribution is the correct distribution to apply. The distribution is transformed by Y=LnX, creating a normal distribution for logarithmic data and the work is done in logarithmic terms, i.e., dB. Only when additive data are used, should the normal (sometimes called Gaussian) distribution be applied. A correct method using logarithmic (multiplicative) data is shown, and some common errors in using linear (additive) data are mentioned