Magnetic anomaly signal detection (MASD) is a passive method for the detection of visually obscured ferromagnetic objects. This paper proposes a new method for MASD based on the ambient field of power frequency magnetic (power transmission line system). Moreover, a new information extraction technique is extended by employing Synchrosqueezed Wavelet Transform (SSWT) to improve the accuracy of the MASD method. With the extended information extraction technique, the time-frequency information of the anomalies can be efficiently distinguished from the power frequency magnetic anomaly signal. The multi-component of the time-frequency information is separated by extracting the time-frequency ridges in the spectrogram. The complexity of time-frequency information is evaluated using Rayleigh entropy. Compared with the continuous wavelet transform and short-time Fourier transform, the Rayleigh entropy of our method is reduced by 4.1886 and 4.3623, respectively. Finally, the efficiency of the new method is verified by the outfield experiments.

Aiming at the problem that traditional underwater detection technology has been unable to meet the detection requirements, a new type of power-frequency (50Hz) magnetic field detection method is proposed. The space power frequency magnetic field model of the ferromagnetic cylindrical underwater target is deduced, and the magnetic anomaly of the ferromagnetic cylindrical underwater target rotating 0°, 30°, and 90° along the axis direction under the background of the power frequency magnetic field is simulated. The field distribution is further analyzed for the three-component magnetic anomaly spatial distribution law of ferromagnetic underwater targets. Through experiments on the scaled model, the magnetic induction intensity of the scaled model is measured, and the correctness and consistency of the spatial distribution of the power frequency magnetic anomalies of the ferromagnetic cylinder are verified, which is provided thinking for the design of power frequency electromagnetic detection of underwater targets.