Article 1) researches the spectrum of different time dependent oscillations of economic variables in the economics, 2) introduces the notion of the Ledenyov discrete time signals in the economics for the first time, 3) proposes the Ledenyov discrete time signals theory in the nonlinear dynamic economic system for the first time, 4) describes the developed software program to forecast the business cycles, going from the spectral analysis of the discrete time signals and the continuous time signals in the nonlinear dynamic economic system over the selected time period. Authors show that 1) the discrete time signals and 2) the continuous time signals may be present in the spectrum of the different oscillations of the economic variables in the economies of scale and scope. We assume that 1) the discrete time signals, and 2) the continuous time signals may have the information money fields in agreement with the Ledenyov theory on the information money fields of the cyclic oscillations of the economic variables in the nonlinear dynamic economic system. We developed the MicroSA software program 1) to analyze the spectrum analysis of the cyclic oscillations of the economic variables in the nonlinear dynamic economic system, including the discrete time signals and the continuous time signals; 2) to make the computer modeling and to forecast the business cycles, going from the spectral analysis of the discrete time signals and the continuous time signals in the nonlinear dynamic economic system, for applications by a) the central banks with the purpose to make the strategic decisions on the monetary policies, financial stability policies, and b) the commercial/investment banks with the aim to make the business decisions on the minimum capital allocation, countercyclical capital buffer creation, and capital investments.