一种改善MT低频数据质量的方法及其应用

A METHOD TO ENHANCE QUALITY OF LOW - FREQUNCE MT DATA AND ITS APPLICATION

电磁干扰是影响大地电磁测深方法(MT)数据质量的主要因素。目前,除从仪器电路上考虑压制50Hz的工业干扰外,主要的压制干扰的方法为近、远参考的ROBUST技术。它对高频电磁干扰或随机干扰有明显的压制作用。但在强干扰地区(通常具有很强的低频电磁干扰,如长、短脉冲和方波等低频干扰),低频数据的质量仍然很差。这是因为在低频数据处理时,强的低频电磁干扰使得级联分样后的数据发生了强的崎变,与实际的有用信号相差甚远。从 MT时序数据出发,提出了应用小波变换的方法,重组低频干扰并加以消除,达到提高信噪比的目的。经实际资料处理证明,此方法效果明显。

Electromagnetic disturbance is one of primary factors affecting data quality acquired by MT. In addition to suppressing 50Hz industrial dis-turbance by apparatus circuits, the main method to suppress the disturbance is the near - remote reference Robust technique which effectively suppresseshigh - frequency electromagnetic disturbance or random disturbance. However, it is difficult to enhance data quality in the area affected by strong low -frequency electromagnetic disturbances like long or short impulses and rectangle waves. Those cause series - related decimated data strong aberrant duringthe data processing, and the data have much difference with the usefu1 signals in practice. Based on the time - order MT data, 1ow-frequency disturb-ance signals are reconstructed and eliminated using wavelet transformation in order to increase s/n ratio. This method proves effective during the data pro-cessing in practice.