Abstract. Magnetic interference source identification is a critical preparation step for magnetometer-mounted unmanned aircraft systems (UAS) used for high-sensitivity geomagnetic surveying. A magnetic field scanner was built for mapping the interference that is produced by a UAS. It was used to compare four types of electric-powered UAS capable of carrying an alkali-vapour magnetometer: (1) a single-motor fixed-wing, (2) a single-rotor helicopter, (3) a quad-rotor helicopter, and (4) a hexa-rotor helicopter. The scanner’s error was estimated by calculating the root-mean-square deviation of the background total magnetic intensity over the mapping duration; averaged values ranged between 3.1–7.4 nT. Each mapping was performed above the UAS with the motor(s) engaged and with the UAS facing in two orthogonal directions; peak interference intensities ranged between 21.4–574.2 nT. For each system, the interference is a combination of both ferromagnetic and electrical current sources. Major sources of interference were identified such as servo(s) and the cables carrying direct current between the motor battery and the electronic speed controller. Magnetic intensity profiles were measured at various motor current draws for each UAS and a change in intensity was observed for currents as low as 1 A.

中文翻译：

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用于航空测量的四种类型的无人机系统的电磁干扰图

摘要。磁干扰源识别是用于高灵敏度地磁测量的装有磁力计的无人机系统（UAS）的关键准备步骤。内置了一个磁场扫描仪，用于标测UAS产生的干扰。它被用来比较四种可携带碱蒸气磁力计的电动UAS：（1）单马达固定翼，（2）单旋翼直升机，（3）四旋翼直升机， （4）六旋翼直升机。扫描仪的误差是通过计算整个测绘期间背景总磁强度的均方根偏差来估算的；平均值介于3.1–7.4 nT之间。每次映射都在UAS上方进行，电机处于接合状态，并且UAS面向两个正交方向。峰值干扰强度在21.4–574.2 nT之间。对于每个系统，干扰都是铁磁和电流源的组合。确定了主要的干扰源，例如伺服器和在电机电池与电子速度控制器之间传输直流电的电缆。在每个UAS的各种电动机电流消耗下测量磁强度曲线，并观察到低至1 A电流的强度变化。