Based on the principles derived from Campbell’s theorem, this paper carries out an analysis of the possibilities of Campbell’s mean square value signal processing system. The mean square value mode is especially suitable for measurements performed in a mixed radiation field, because the quantities of electrical charge involved in the interactions of the two types of radiation are substantially different. The measuring detector element may be an adequate ionization chamber and/or semiconductor components for mixed n-γ fields. An examination of the discrimination of gamma in relation to the neutron component in the signal of the detector output was carried out, calculated according to the theoretical model of radiation interaction with the detector. The advantage of the mean square value method was confirmed and it was concluded that the order of n-γ discrimination in mean square value signal processing is greater than the one rendered by the classical measuring method.