Vector Magnetometer Application with Moving Carriers

In magnetic prospecting the aeromagnetic survey is a widespread method used for research in large territories or in the areas with difficult access (forests, swamps, shallow waters). At present, a new type of mobile carriers - remotely piloted vehicles or drones - is becoming very common. The drones supplied by magnetometer can be also used for underground utility location (for example, steel and concrete constructions, buried power cables, to name a few). For aeromagnetic survey, obtaining of 3-component magnetic field data gives higher processing precision, so the fluxgate magnetometers (FGM) seem to be the most preferable by reason of low weight, noise, power consumption and costs. During movement of FGM fixed to a drone practically permanent attitude changes in the Earth's magnetic field arises with corresponding changes of its projection at FGM axes. Also the electromagnetic interference from the drone motor and uncontrolled oscillations of drone and suspension are the factors which limit the magnetometer sensitivity level. Aroused because of this, signals significantly exceed the expected signals from a studied object and so should be removed by proper interference filtration and use of stabilized towed construction, as well as at data processing. To find the necessary resolution threshold of a drone-portable FGM, the modeling was made to estimate magnetic field value from a small sphere about 1 cm radius at the minimal altitude of drone flight and it was shown that such a small object can be reliably detected if the FGM noise level is less than 0.15 nT. Next requirement is the necessity to decrease as much as possible the FGM power consumption with retention of low noise level. Finally, because of drone movement, the broadening of a frequency range should be done. The LEMI-026 magnetometer was developed satisfying all requirements to the drone-mounted device. The field tests were successfully performed using two of LEMI-026 magnetometers and it was concluded that the parameters of these magnetometers allow their using for the magnetic survey with moving platforms.