Weak pulse signal detection method based on improved strongly coupled oscillators

Abstract

A strongly coupled oscillator can be used to detect weak pulse signals and recover waveforms, but its detection frequency of weak pulse signal is limited by the system’s built-in frequency. With a fixed built-in frequency, the system can only effectively detect and recover pulse signals in a certain frequency range, and waveform distortion occurs when pulse signals of higher frequencies are detected. In this work, the relationship between the built-in frequency of the coupled oscillator and the frequency detection range of weak pulse signal is analyzed, and two kinds of improved strongly coupled oscillator structures are proposed to extend the frequency detection range of weak pulse signals. By introducing the nonlinear restoring force coupling term, the nonlinear restoring force strongly coupled oscillator can effectively retain the high-frequency component of the signal, and can also better retain the signal characteristics when the pulse signal is input at a higher frequency. By introducing the Van der Pol-Duffing oscillator, the two-oscillator strong coupling system strengthens the stability of the internal structure of the system, and also achieves the effect of expanding the frequency detection range of the pulse signal. In addition, based on the variable iteration step size and frequency correlation of chaos detection, a method of detecting unknown frequency pulse signals is proposed. Instead of changing the built-in frequency of the system for frequency scanning, the method of changing the iteration step size is used. And using the frequency correlation of chaos detection, the correlation coefficient of the received signal and the recovered signal is compared with the correlation coefficient of the pure noise input case, then the pulse signals can be effectively detected based on the apparent difference between the two correlation coefficients. It is verified by simulation experiments that the proposed method can effectively detect the pulse signal of unknown frequency, and the proposed improved strong coupling oscillator has a greater performance improvement than that of the strong coupling oscillator.