摘要
同步挤压S变换是一种处理非平稳信号的新时频变换方法,通过"挤压"信号的S变换结果,可以得到高分辨率的时频谱.但是,当信号的相位随时间呈非线性变化时,同步挤压S变换计算出的瞬时频率会出现误差,并造成时频谱分辨率降低.为了改善其对于该类信号的时频分析效果,我们利用时间和频率的二阶偏导数对瞬时频率计算式进行修正,提出二阶同步挤压S变换.合成信号处理结果表明,二阶同步挤压S变换的分辨率不但明显高于常用时频变换,在信号瞬时频率随时间呈二次或正弦变化的情况下,其时频挤压效果也好于同步挤压S变换.我们将二阶同步挤压S变换应用到天然气地震勘探资料的谱分解当中,结果表明,二阶同步挤压S变换可以很好地检测到与天然气相关的谱异常.因此,二阶同步挤压变换对于地震解释是一种很有潜力的方法.
The Synchrosqueezing S-transform （SSST） is a novel approach for time-frequency（T-F） representation of non-stationary signals. By ＂squeezing＂ T-F spectrum of the S-transform （ST） of a signal, the SSST can obtain a high-resolution T-F spectrum. However, when the phase of a signal varies non-linearly with time, the instantaneous frequency （IF） of the signal calculated by the SSST would be inaccurate, causing reduction of the resolution of the T-F spectrum. In order to improve its performance in imaging such signals, we modify the formula of IF with the help of the second-order partial derivatives of time and frequency, and propose a second-order Synchrosqueezing S- transform （SSST2nd）. Synthetic examples show that the SSST2nd not only has obviously higher resolution than commonly used T-F transforms, but also images the signals of which the IFs vary quadratically or sinusoidally with time better than the SSST. We apply the SSST2nd tO perform spectral decomposition of seismic data for natural gas exploration. The results illustrate that the SSSTe.d can be used to well detect frequency spectral anomalies correlated with natural gas accumulations. Therefore, it can be concluded that the SSST^a is a good potential technique for smsmm lnterpretauo.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第7期2833-2844,共12页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(41230318
41074077)
中央高校基本科研业务费专项(201413004
201564006)
高等学校博士学科点专项科研基金(20130132110023)
山东省自然科学基金(ZR2014DP001)联合资助
关键词
时频变换
二阶同步挤压S变换
频谱异常
地震资料
谱分解
Time-frequency transform spectral anomaly
Seismic
Second-order Synchrosqueezing S-transform
Frequency data
Spectral decomposition
