This paper deals with the analysis of reactor modulation experiments for code validation in the framework of the Horizon 2020 European project CORTEX. The analysis is based on a statistical based approach on spectral powers and their phase shift angles calculations. The treatment of individual oscillations as independent aids in elimination of possible biases and correlations of consecutive oscillations. Results from one of the experimental campaign per- formed at the AKR-2 and CROCUS reactors are also presented.