Portable node-based wide field electromagnetic system
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.