摘要
广义S变换是一种优于短时窗傅立叶变换和小波变换的时频分析方法,利用广义S变换能够准确定位大地电磁资料中存在的噪声,通过定义时频窗对噪声进行滤除,从而明显提高阻抗视电阻率与相位的估算质量.本文基于S变换和大地电磁测深资料处理的基本原理,研究了基于广义S变换的大地电磁测深资料的处理流程和方法.对理论模拟信号及实测大地电磁场时间序列数据的处理,证实了方法的有效性.
S transform is time-freq domain analysis method. It was proposed by Stockwell and others in1996. S transform which is one of time-frequency analysis methods is better than short-time Fourier transform and wavelet transform, the method absorbs the advantages of the both methods and compensates for both methods insufficiency. Later, some scholars put forward the improvement of S transform and proposed generalized S transformation. Using the generalized S transform can position the noise accuratly which exists in the time series data, and also can filter out the noise by defining appropriate time-freq window, so it can obviously improve the estimated quality of needed valid data. Today, Fourier transform applys to the electromagnetic spectrum analysis of time series mostly, but Fourier transform just displays each frequency value of overall intensity in the whole time domain In order to improve the estimated quality of the impedance, apparent resistivity and phase of magnetotelluric sounding data, the paper base on the S transform and the basic processes principle of magnetotelluric sounding data and adjusts the factors of generalized S transform for achieving better resolution, so that we can obtain the impedance of each fixed-frequency of each time point and we also can observe the location of noise energy in the time domain and frequency domain by using the generalized S transform, then we can filter out the noise which we do not need. The feasibility of the generalized S transform method is confirmed by the result of processing the theory signal without noise and the theory signal containing noise. Paper design measured data processing cycle for comparison the results of apparent resistivity images of generalized S transform with the result images of SMT2000, the validity of the generalized S transform method is confirmed by the result of measured magnetotelluric time-series data.
出处
《地球物理学进展》
CSCD
北大核心
2012年第3期988-996,共9页
Progress in Geophysics
基金
国家专项"深部探测技术与实验研究"(编号:SinoProbe-01
201011035
201011036)
国家自然基金委(40974060
40774051)
中国地质科学院地质研究所基本科研业务费(J0915)共同资助
关键词
S变换
广义S变换
大地电磁测深
噪声
S transform, generalized S transform, magnetotelluric sounding, noise
