Faced with the more insidious electricity stealing methods of high-frequency pulsed magnetic field

anti-theft detection based on magnetic field signals would fail due to noise. Aiming at this problem

a method combining SVD and wavelet transform is applied to anti-theft devices and proposed to remove noise and separate stolen electricity signal in detection. Firstly

the noisy magnetic field mixed signal is transformed by FFT to obtain the power spectrum

and the classical threshold is introduced to determine the number of narrow-band noises and the effective rank order of the SVD.Then the mixed signal is SVD decomposed

the singular value corresponding to the narrow-band noise is reset to zero

and then the signal is reconstructed. Finally

wavelet transform is used to remove the influence of random noise. Simulation and experimental results show that

this method can be effectively applied to the detection of electrical stealing. Compared with FFT threshold filtering method and EMD method

the suppression effect of the proposed method is more prominent.