Abstract
The low-frequency electromagnetic fields and magnetic anomalies generated by ships and other underwater platforms are widely recognized as important features for ocean target detection. Low-frequency magnetic fields and anomalies are typically measured by optically pumped magnetometers installed on aircraft. However, the interference that is generated by the aircraft platform may significantly affect the detection performance. The traditional aeromagnetic compensation model has a good effect on eliminating the interference magnetic field that is caused by the carrier attitude variation. Usually, the magnetometer is fixed at the top of a long probe on the aircraft to avoid the influence from the main body in the aircraft. However, the probe is sensitive to external vibrations, and vibration-induced magnetic interference can occur in the measurements. The magnetometer is especially easily affected by the interference magnetic field, including the vibration frequency and harmonic frequency of the probe, in a moving platform, such as a helicopter. These interference fields usually have independent frequency characteristics that can be eliminated by compensation methods. In this paper, we propose a method based on the improved coherent noise suppression method with a pair of magnetometers to eliminate the effects from these magnetic field disturbances and improve the detection performance of the measurement system. The results of the flight experiment show that the method can effectively eliminate low-frequency vibration interference and improve the detection ability of weak signals from targets.
Highlights
The electromagnetic fields generated by naval vessels and other underwater carriers have become important signals for tracking targets of interest in marine warfare [1,2]
In order to eliminate the electromagnetic interference field that is produced by the vibration of the helicopter platform, in this paper, we propose an interference cancelation algorithm based on the improved coherent noise suppression (ICNS) method for a detection system with a pair of magnetometers
In order to further prove the effectiveness of the ICNS method proposed in this paper, Section 5.2 presents a simulation target design for the low-frequency magnetic field detection experiment to verify the effectiveness of this method
Summary
The electromagnetic fields generated by naval vessels and other underwater carriers have become important signals for tracking targets of interest in marine warfare [1,2]. In order to protect the hull from corrosion, the impressed current cathodic protection system and the sacrificial anode cathodic protection system are widely used to generate corrosion protection currents in modern ships. These currents create electro-static and magneto-static anomalies around the ships. The signals can be transmitted several kilometers away They are considered important signal sources for detecting underwater military targets [5]
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