关键词: 瞬变电磁, 教学模型, 异常线圈, 复杂可编程逻辑器件

Abstract: In order to meet the practical teaching needs of the geoscience instrument course，a transient
electromagnetic experiment teaching model system is designed． It includes four parts: a transmitting /receiving
integrated machine，a receiving sensor，an abnormal coil and a host computer control software． The transmitting /
receiving integrated machine uses the AＲM ( Advanced ＲISC Machine ) controller and CPLD ( Complex
Programmable Logic Device) as the main control unit，and drives the H-type full-bridge circuit to realize the
generation and transmission of a bipolar square wave． The high-sensitivity is designed using the differential
hollow coil and the amplifier circuit for the dual op amp sensor． By studying the relationship between the induced
electromotive force of the closed coil and the time constant，an abnormal coil is used to simulate a good
conductive finite conductor． The host computer control software is developed on the Visual Studio platform using
C # language． After testing，this model can collect and display the transient electromagnetic induction secondary
field attenuation signal curve in real time，realize the simulation of the working process of the transient
electromagnetic instrument in the laboratory，and have a certain auxiliary effect on the practical teaching of the
course．

Key words: transient electromagnetic methods ( TEM) , teaching model, anomaly coil, complex programmable logic device ( CPLD)