论文部分内容阅读
天然大地电磁场信号微弱,极化方向随机,极易受电磁噪声污染。矿集区人烟稠密、工业发达,区内强烈的工业、通讯、矿山、民用等电磁干扰严重污染了大地电磁测深数据。本文利用数学形态学从受严重污染的电磁场时间序列中提取出类方波、三角波、阶跃、脉冲和充放电5种典型噪声的波形,以不同的方式将这些噪声波形与区内基本未受噪声污染的测点(D1139)的电磁场波形叠加,对比分析了不同采样率加噪后D1139点的测深曲线的变化。结果表明:24Hz采样率,方波噪声、三角波噪声、阶跃噪声、充放电噪声等会使得视电阻率、相位曲线出现类似近源干扰特征,脉冲噪声使测深曲线出现畸变;320Hz采样率,方波没有明显影响,三角波、阶跃噪声、脉冲噪声使曲线部分频点出现跳变,而充放电噪声会使曲线出现类似近源干扰特征;2560Hz采样率,方波、充放电噪声没有明显影响,三角波、阶跃噪声、脉冲噪声则使曲线出现了不同程度的畸变。
The signal of natural earth electromagnetic field is weak, the polarization direction is random, and it is highly susceptible to electromagnetic noise pollution. The densely populated mining area and the developed industry have led to the serious pollution of the earth’s electromagnetic sounding data by the electromagnetic interference caused by the intense industrial, communications, mining and civil affairs in the area. In this paper, five kinds of typical noise waveforms, such as square wave, triangle wave, step, pulse and charge and discharge, are extracted from the time series of severely polluted electromagnetic fields using mathematical morphology. These noise waveforms are compared with those in the region The electromagnetic field waveforms at the point of noise pollution (D1139) are superposed, and the changes of the sounding curve of D1139 at different sampling rates plus noise are compared and analyzed. The results show that the sampling rate, square wave noise, triangular wave noise, step noise, charging and discharging noise, etc. Will make the apparent resistivity and phase curve similar to near - source interference. The pulse noise makes the sounding curve distortion. The sampling rate of 320Hz, The square wave has no obvious effect. Triangle wave, step noise and impulsive noise make the transition of the frequency part of the curve appear. The charging and discharging noise will make the curve appear similar to the near-source interference. The sampling frequency of 2560Hz, square wave and noise of charging and discharging have no significant effect , Triangular wave, step noise, impulsive noise make the curve appeared different degrees of distortion.