Magnetic Anomaly Detector (MAD) is an instrument used to detect minute variations in the Earth’s magnetic field. Magnetic anomaly detection systems are used by military, difence, aerospace, and navy authorities to detect submarines. The military Magnetic Anomaly Detector gear is a descendent of geomagnetic survey instruments used to search for minerals by the disturbance of the normal earth-field. Smartphone Magnetic Anomaly Detector (MAD) measures differences in magnetic field strength using the iPhone 3GS magnetometer. Smartphone applications (apps) are available for iPhone and iPad tablet PCs for magnetic anomaly detection.

The primary application of magnetic anomaly detector is to detect the submerged submarine. Usually this task is executed from aircrafts using airborne magnetic anomaly detection systems which uses the principle that metallic objects disturb the magnetic lines of force of the earth. A mass of ferromagnetic material creates a detectable disturbance in the magnetic field.

Light, radar, or sound energy cannot pass from air into water and return to the air in any degree that is usable for airborne detection. The lines of force in a magnetic field are able to make this transition almost undisturbed, however, because magnetic lines of force pass through both water and air in similar manners. Consequently, a submarine beneath the ocean’s surface, which causes a distortion or anomaly in the earth’s magnetic field, can be detected from a position in the air above the submarine. The detection of this anomaly is the essential function of MAD equipment.

Magnetic anomaly detection has traditionally been associated with submarine detection and overlooked as a possible solution for land-based surveillance and detection. Recent conflicts have demonstrated the need for enhanced detection capabilities. CAE has been evaluating the potential use of MAD technology for the detection of concealed metal objects on land. With a MAD system mounted on some type of ground vehicle or unmanned aerial vehicle (UAV), the system could detect a variety of targets, such as armoured vehicles or artillery. The MAD system is capable of detecting metallic objects through walls, buried underground, or hidden in dense forest canopies.