Abstract:

For the detection of weak signals in strong noise background, a novel method with united denoising and frequency modulation is proposed based on the conventional detection method. The joint denoising system combines autocorrelation and wavelet threshold transformation, so the negative impact from the noise is avoided greatly in the detection result. Using standard signals with adjustable frequency to modulate the measured signal frequency, thus the frequency difference of the standard signals and the measured signals meets the testing conditions. It breaks the restrictions of the Duffing oscillator, which can only detect signals with the frequency similar to the system driving force. The two-oscillator-difference method is more intuitive, with good antinoise performance ability, and the relative error is controlled under 5%. The system has a strong anti-interference ability, and the minimum signal-to-noise ratio can reach -41 dB. The feasibility and validity of this method are proved by the simulation results.