Spectral decomposition based on oscillator-array model

On the basis of the actions of a signal upon an ideal oscillator and an oscillator-array, the instantaneous energy density spectrum of a signal is defined. Furthermore, definitions of the instantaneous energy, the power density spectrum, the power, the total energy density spectrum and the total energy of a signal are introduced. Properties of power density spectrum and the relations between the power density spectrum and other physical quantities are presented. To meet the needs of real applications, an improvement method to the power density spectrum has also been mentioned.