The present application belongs to the field of weak
harmonic signal detection, and particularly to a weak
harmonic detection method based on Chen
system. The parameters a, b, c and the initial value (x0, y0, z0) of the
system of the Chen
system are set, the
critical threshold of the
control signal of the system is found out by using the dichotomy according to the
bifurcation diagram of the system
state variable changing with the amplitude f of the
control signal, and the input
signal weighting factor A is set according to the
critical threshold. After the Chen system for
signal detection is debugged, the
control signal and the weighted input signal are input into the system at the same time, the system equation of the Chen system is solved, the x-z
phase diagram of the system, the
attractor distribution and the
state variable time history diagram are drawn. The change of the fixed point position or the change of the
attractor distribution of the system is judged, if the change occurs, the
harmonic signal to be detected exists, at this time, the control signal amplitude f is reduced by a step and the system state is recalculated until the fixed point position or the
attractor distribution of the system becomes the initial state, and the ratio of the difference of the control signal amplitude and the weighting factor is the amplitude of the harmonic signal to be detected. The signal can be detected without error under the
noise of-60dB, and the detection error under the
noise of-100dB can also be kept below 0.1%.