Weak magnetic anomaly signal detection based on the entropy of mixed differential signal

Abstract

Magnetic anomaly detection is of great significance in geological exploration and underwater target detection. However, the magnetic anomaly signal is not easy to be detected because of its weakness relative to the magnetic environmental noise, and the detection probability of the magnetic anomaly signal is affected by signal frequency. We propose a mixed differential minimum entropy method which can detect the weak magnetic anomaly signal. The proposed method combines the coherence difference method with the synchronous reference subtraction method in preprocess, which can suppress common-mode noise in the signal and relax the limitation of the frequency of the magnetic anomaly signal on the detection ability. Using the concept of entropy to describe the preprocessed signal can eliminate the residual high-frequency noise and further improve the signal-to-noise ratio of the target signal. Results show that the proposed method may effectively improve the signal-to-noise ratio and increase the frequency range of the magnetic anomaly signal, which has better detection performance than that of traditional method.