Amplitude modulation based on time-varying forced function of second-order oscillator circuit

This paper presents a novel technique of amplitude modulation which is based on a second-order oscillator circuit. By using the multi-time technique to analyze a second-order system for time-varying forced function, it is found that the system´s forced response not only at an initial time but also at any arbitrary time is presented in term of the natural response´s magnitude. It implies that amplitude of the natural response can directly be controlled by the forced response. For a condition that the forced response and the time-varying forced function is approximately identical, the resulted complete response of the second-order system therefore is amplitude modulation where the natural response and the time-varying forced function respectively represents sinusoidal carrier and information signals. To confirm the proposed technique, experimental results have been demonstrated which agree well with the given theoretical analysis