大地电磁测深曲线平滑尺度

Smoothing scale of magnetotelluric sounding curve

在大地电磁测深中由于噪声干扰常使得观测的信号发生畸变,严重地影响了信号的分析,因此如何有效地对噪声干扰进行滤波及怎样选择滤波时间尺度是当前数据处理中的难点。利用各向异性扩散(Anisotropic Diffusion,AD)及扩散平衡(Diffusion Balance,DB)方法在噪声压制与信号特征的保护及形态特征的恢复上达到了合理的平衡。模拟与实测数据显示:利用AD与DB可使平滑后的信号与原始信号达到高精度的逼近,信噪比从14.19 dB提高到69.25 dB;扩散平衡时间与噪声强度密切相关,噪声强度越高达到扩散平衡的时间越长;有效地压制了实测信号中的“飞点”干扰,恢复了信号的基本形态。

Measurement signal is often distorted by noise, which seriously influences signal analysis in magnetoteUurie sounding. One of important current questions is that how to falter and select a filter time scale in the data processing. In this paper de-noising, feature preservation and shape restoring of signal are reasonable balanced by anisotropic diffusion（AD） and diffusion balance （DB）. Simulation and field data show： （ 1 ） filtered signal is accuracy approximated to the original signal and SNR（ signal noise ratio） is up to 69.25 dB from 14.19 dB by AD and DB; （2） diffusion balance time scale is closely related to noise intensity, the more noise, the more diffusion balance time scale; （3） ＂outliers＂ are effectively removed and basic shape of signal is restored in the field data.