便携式节点化广域电磁探测系统

Portable node-based wide field electromagnetic system

传统人工源电磁法必须采集特定方位的电磁场实现探测,观测系统严苛,在地形地物复杂区人为误差大,导致视电阻率计算不准确.为解决该问题,本文提出宽方位电磁探测方法,定义任意电磁场的视电阻率参数,打破坐标系禁锢,实现任意电磁场的对地探测,观测系统灵活;基于伪随机信号混合编码和FPGA合成技术研发了大功率高效率电磁发射机,实现了复杂伪随机信号的动态装载,具有频差小、频率密度高、可根据探测目标动态调整发射频率的特点;研发了便携式节点化电磁采集仪,采用手机APP实现高精度导航定位、状态监控和采集控制,实现了数据采集的自动化.集成的便携式节点化广域电磁探测系统具有自动化程度高、人为误差小等优点,可实现360°全方位测量,为高效精细电磁探测提供技术装备支持,已成功应用于川藏铁路德达隧道探测.

The traditional controlled source electromagnetic method requires the collection of specific orientation electromagnetic fields for detection,and the observation system is stringent.In areas with complex terrain and geological features,human errors are significant,resulting in inaccurate apparent resistivity.To address this issue,this paper proposes a wide-azimuth electromagnetic exploration method that defines the apparent resistivity of arbitrary electromagnetic fields.This approach breaks free from coordinate system constraints and enables exploration of arbitrary electromagnetic fields with a flexible observation system.Furthermore,based on pseudorandom signal mixed coding and FPGA synthesis technology,a high-power and high-efficiency electromagnetic transmitter has been developed.This transmitter allows for dynamic loading of complex pseudorandom signals with small frequency differences,high frequency density,and the ability to dynamically adjust the transmission frequency according to the exploration target.In addition to this development,a portable node-based electromagnetic data acquisition instrument has been created.It utilizes a mobile app for high-precision navigation positioning and data acquisition control,which enabling automated data collection.The integrated portable node-based wide filed electromagnetic system offers advantages such as high automation levels and minimal human error.It can achieve 360°full-azimuth measurement and provides technical equipment support for efficient and precise electromagnetic exploration.Notably,it has already been successfully applied in the exploration of the Deda tunnel on the Sichuan-Tibet Railway.