It is well-known in radio-electronics that signal for modulation determines the "factor of noise protection" Usually a electromagnetic transformers are using the amplitude modulation when the strength of the primary current is changing by means of variable amplitude of voltage. But it is a modulation with a factor that is equal to unity (k=1). Another type of modulation allows to get the signal/noise ratio less than unity, for example, it is the frequency modulated signal.

By induction law, it is necessary to create the change of density of energy in space. In the case of
electromagnetic induction it is necessary to create the change of density of current in the primary coil wire. It can be created by means of pulsed modulation of the signal. Note that it is necessary to
consider the process of electromagnetic induction in the transformer as a process of information exchange to find optimal modulation type. Fig. 1 shows how voltage is changing to
create density of current changes
 

For any pulse exist the front (density of current is increasing) and abatement (density of current is decreasing) but if the transformer is not high frequency the front and abatement changes are not connected with induction effect. Power in secondary coil for that sort of system is the result of
sum (total) changing current density. By this way it is possible to create an over unity system since the counter-flux of the secondary coil corresponds to "imaginary" summary flux changes and does not correspond to real front/abatement of the pulses.