Powerline interference in the controlled source electromagnetic method has traditionally been one of the biggest conundrums plaguing geophysicists, and its conventional denoising methods primarily include filtering and noise estimation. The filter method leaches noise at specific frequency points, which might also filter useful signals; the noise estimation method significantly eliminates interference, whereas the premise is that the noise is stable after a short time and a recorder is necessary in the field. In the present study, using the periodicity and symmetry of powerline noise, we propose a subtraction and an addition method for cancellation of the powerline noise. First, the transmitted signal is optimized so that the equivalent transmitted signal is an m sequence; then the response signal is processed by using the cancellation method; subsequently, the correlation identification is applied and finally, we solve the earth impulse response by means of the Wiener filter deconvolution method. Simulation experiments and field data tests demonstrate that the powerline noise can be well suppressed by the cancellation method proposed in the present study, so that the system identification accuracy is greatly improved. The method is simple in principle and effective in removing powerline noise, which presents a novel perspective on noise elimination for system identification.

中文翻译：

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电力线噪声消除法在可控源电磁法相关性识别中的应用

受控源电磁法中的电力线干扰历来是困扰地球物理学家的最大难题之一，其常规去噪方法主要包括滤波和噪声估计。滤波方法滤除特定频率点的噪声，也可能滤除有用信号；噪声估计方法显着消除了干扰，但前提是噪声在短时间内稳定，现场需要记录仪。在本研究中，利用电力线噪声的周期性和对称性，我们提出了一种用于消除电力线噪声的减法和加法方法。首先，对发射信号进行优化，使等效发射信号为m序列；然后使用对消方法对响应信号进行处理；随后，应用相关识别，最后，我们通过维纳滤波器反卷积方法求解地球脉冲响应。仿真实验和现场数据测试表明，本研究提出的消除方法可以很好地抑制电力线噪声，从而大大提高了系统识别精度。该方法原理简单，去除电力线噪声有效，为系统识别的噪声消除提供了新的视角。使系统识别精度大大提高。该方法原理简单，去除电力线噪声有效，为系统识别的噪声消除提供了新的视角。使系统识别精度大大提高。该方法原理简单，去除电力线噪声有效，为系统识别的噪声消除提供了新的视角。