Duffing oscillator weak signal time domain detection method based on phase-locked loop

Abstract

The invention relates to a weak periodic signal detecting method based on a phase-locked loop and a Duffing oscillator, and belongs to the field of signal processing. According to the method, the phase-locked loop and the Duffing oscillator are used for setting up a combined weak signal detecting system; signal frequency is detected through the phase-locked loop to detect weak periodic signals with unknown frequency; according to the curve characters of a time history of chaotic signals, and a sequence diagram method and a phase plane diagram method are matched to serve as the criterion for detecting a system state and detecting whether the system state changes or not; a precise threshold value at which the system jumps into a periodic state from a chaotic state is obtained, and the threshold and quality for detecting the weak periodic signal are improved. Compared with a traditional method, the weak periodic signal detecting method can detect the signals with the unknown frequency, is easier to implement, saves a lot of simulation time, is of great signification in practical application and thereby has very good application prospects.

Description

technical field [0001] The invention relates to the field of signal processing, in particular to a method for detecting weak periodic signals. Background technique [0002] The traditional weak signal detection method is very poor in detecting signals with extremely low signal-to-noise ratio, while the Duffing oscillator chaotic system has the advantages of extreme sensitivity to initial values ​​and good immunity to noise, etc., and can show excellent performance in detecting weak signals Good detection effect. As a new weak signal detection method, the chaotic oscillator method does not eliminate the noise, but extracts the signal from the noise background. Due to its uniqueness, it can be applied to practical engineering, including nanovolt-level weak signal detection, rotor early Fault diagnosis, early fatigue crack detection of gears, automobile flywheel housing detection, digital watermarking, ultrasonic leak detection, narrow-band interference of partial discharge of...

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Problems solved by technology

Accordingly, some scholars proposed a new threshold discrimination method (Liu X, Wang C, Xiao B. Research on Chaotic Threshold Criterion Based on the Difference of Solution[C] / / Control Engineering and Communication Technology (ICCECT), 2012International Conference on.IEEE,2012:228-23), this method has a simple algorithm and reduces the amount of calculation, but it cannot accurately identify the state of the system in the critical state, so it is difficult to apply in practice

The intuitive method is to determine the presence or absence of chaos only by observing the time-domain or frequency characteristic curve of the analyzed signal, and the traditional intuitive method of measuring the amplitude of the signal to be measured by observing the phase transition of the system lacks a quantitative basis for judgment, and consumes a lot of machine memory. In order to judge more accurately, the simulation time will be increased blindly

The timing diagram method has a fast calculation speed, and the oscilloscope can be used to detect the output status of multiple signals at one time, which consumes less time and has high efficiency. However, when the system is in a critical state, the waveforms of the timing diagram are various, and sometimes it is difficult to distinguish which state the system is in.

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