| Summary: | For weak signal detection with known frequency, based on the double coupling Duffing oscillator method, a differential double coupling Duffing oscillator and Van der Pol-Duffing oscillator detection method is proposed. Its feasibility is verified by sinusoidal analog signal. It has intuitive detection effect and high sensitivity, and can detect weak signal with lower signal-to-noise ratio (SNR). For underwater acoustic weak signal detection with unknown frequency, based on the above proposed method, a differential double coupling Duffing oscillator and Van der Pol-Duffing oscillator variable step-size detection method is proposed. Compared with the existing double coupling Duffing oscillator variable step-size method and differential double Duffing oscillator variable step-size method, its SNR threshold is respectively reduced by 6.02dB and 2.28dB. The lowest average error rate of frequency estimation in multiple sinusoidal analog signal detection under Gaussian white noise, Gaussian color noise and Rayleigh distribution noise is 0.423%. Its detection effect is verified in the detection of measured underwater acoustic signals from the website http://atlanttic.uvigo.es/underwaternoise/. The results show that it has good detection performance. It provides a new detecting method for underwater acoustic weak signal. In the future, it can be applied to detect weak periodic signal such as square wave and general periodic signal with unknown frequency.
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