Apparent resistivity is a critical parameter for providing information about underground structures. Since the fields of the transient electromagnetic method (TEM) are an implicit function of resistivity, full-time apparent resistivity definition has always been one of the difficult issues. Besides, the definition of TEM apparent resistivity was always based on the magnetic field. However, the multi-channel transient electromagnetic method (MTEM) mainly collects electric fields, of which the apparent resistivity definition is much more difficult. In this paper, the definition of the MTEM full-time apparent resistivity is mainly investigated. First, we briefly introduces the MTEM principles. Subsequently, a detailed study on the definition of MTEM full-time apparent resistivity is carried out. The analysis of theoretical expression of the impulse response in uniform half-space shows that the electric field is a non-monotonic function of the resistivity. Although the apparent resistivity can be obtained by dividing the calculation interval into two monotonic intervals, there will be a false anomaly in the apparent resistivity curve. In searching for a better definition, we obtain the step-off response by integrating the impulse response. The step-off response is still a non-monotonic function, and there is also distortion in the apparent resistivity curve. However, the expression of step-on response is a monotonic function, and there is no false anomaly in the apparent resistivity curve. It is well known that the sum of the step-off response and the step-on response is constant at any time, and apparent resistivity of the early time is equal to the first layer resistivity. Through the above relationship, we can obtain the step-on response using the impulse response, and then calculate the apparent resistivity. The algorithm is verified through numerical simulation and field tests.

视电阻率是提供有关地下结构信息的关键参数。由于瞬变电磁法（TEM）的领域是电阻率的隐含函数，因此，全时表观电阻率定义一直是难题之一。此外，TEM视在电阻率的定义始终基于磁场。但是，多通道瞬变电磁法（MTEM）主要收集电场，其表观电阻率定义要困难得多。本文主要研究MTEM全时视电阻率的定义。首先，我们简要介绍MTEM原理。随后，对MTEM全时视电阻率的定义进行了详细研究。对均匀半空间中脉冲响应的理论表达式的分析表明，电场是电阻率的非单调函数。尽管可以通过将计算间隔分为两个单调间隔来获得视在电阻率，但是在视在电阻率曲线中会出现错误的异常现象。在寻找更好的定义时，我们通过整合脉冲响应来获得阶跃响应。阶跃响应仍然是非单调函数，并且在视电阻率曲线中也存在失真。但是，阶跃响应的表达是单调函数，并且在视电阻率曲线中没有错误的异常。众所周知，阶跃响应和阶跃响应之和在任何时候都是恒定的，早期的视电​​阻率等于第一层电阻率。通过以上关系，我们可以利用脉冲响应获得阶跃响应，然后计算视在电阻率。通过数值模拟和现场测试验证了该算法。