The author has presented a short history of the Economic Geography Department of the Cracow University of Economics in the years 1958–2018. The scientific and didactic staff, its basic journalistic achievements and the main didactic activity were presented.

The paper describes second order generalized integrator (sogi) which is specialized in band-pass filtering and orthogonalization of periodic signals. Modifications of the structure and the influence of parameters on the system performance is described. The article highlights the particular importance of model discretization method in the practical implementation, as well as reviews estimation methods of the: amplitude, frequency, offset and phase angle of the periodic signal. Examples of simulation and experimental results are presented.