无人飞艇长导线源时域地空电磁勘探系统及其应用

Development and application of the grounded long wire source airborne electromagnetic exploration system based on an unmanned airship

以无人飞艇作为载体的时域地空电磁探测系统,具有高效、低成本、勘探深度大和空间分辨率高等优点.本文基于二维有限差分方法,分析了长导线源地空电磁响应的特征和变化规律、以及飞行高度的影响;在此基础上,采用32位Cortex-M3内核处理器,以全差分模拟前端压制电磁干扰,实现了24位低噪声多通道海量电磁数据的同步采样及存储,研制了一套可搭载于无人飞艇的时域电磁接收系统,并基于Wi-Fi Mesh无线多跳网络实现了地面远程监控.通过分析飞艇发动机的电磁噪声特点,采用独立分量分析法进行实测数据的噪声去除.研制的地空电磁接收系统使用无人飞艇搭载,在江苏省南通市如东县和内蒙古巴彦宝力格地区进行了电磁探测实验,地空电磁勘探结果与地面瞬变电磁和大地电磁方法进行了对比,证明了地空电磁探测方法的有效性.无人飞艇时域地空电磁探测系统的成功飞行实验,为在我国草原沙漠地区、海陆交互地带、沼泽地带、无人山区等特殊景观地区开展矿产资源、水资源、地质灾害等电磁探测提供了新方法和新思路.

The time-domain semi-airborne electromagnetic system mounted on an airship has outstanding efficiency,low costs and high depth of exploration.Using a 2D FDTD method,this study analyzes the characteristics and variation rules of grounded long wire source airborne electromagnetic responses,and the effect of flight altitude.A receiver is developed on an unmanned airship,using a 32bit MCU with the Cortex-M3 processor,reducing electromagnetic noise by placing a fully differential amplifier in the front of the analog circuit,and recording multi-channel signals synchronously with 24-bit resolution.To achieve ground remote control,we establish a high-speed communication network through WiFi-Mesh connection based on multihop topology.To reduce noise,a method based on ICA is used according to the characteristics of the engine noise analysis.We have carried out two survey tests in a region of Nantong and a pastoral area in Inner Mongolia using the developed receiver on the unmanned airship,and compared the exploration results using the grounded long wire source airborne electromagnetic system,TEM,and MT system.The results indicate that the grounded long wire source airborne electromagnetic method is practical and effective.With the successful flight tests of the developed system,it can be used as a new approach for investigations in deserts,costal beaches,swamps and mountains.