摘要： 在低信噪比时，短时傅里叶变换和实小波变换无法准确提取钻头进入不同地层的时延信息。为此，提出一种复小波变换分析法。利用幅值和相位信息对信号突变点进行提取和定位，从而实时判断钻头钻进目的层的时刻。实验结果表明，该方法能准确表征振动信号的时频特征，与短时傅里叶变换和实小波变换相比，具有更好的时间定位和抑噪能力。

关键词: 复Morlet小波, 短时傅里叶变换, 实小波变换, 振动信号, 地层识别, 相位

Abstract: According to the bit excited in the layers with different characteristics of the vibration signal, the delay information of the bit into an another stratum can not be extracted accurately by real Short Time Fourier Transform(STFT) and wavelet transform in the case of low SNR. This paper puts forward a complex Morlet wavelet transform analysis. The message of the amplitude and the phase has a good sensitivity to the mutation, so the mutation position can be extracted and then the time when the drilling bit is into different stratum is determined in real time. Experimental result prove that complex Morlet wavelet transform can accurately characterize the time-frequency information and the delay time information. Compared with the STFT and the real wavelet transform, complex Morlet wavelet transform has a better time localization and noise suppression capabilities.

Key words: complex Morlet wavelet, Short Time Fourier Transform(STFT), real wavelet transform, vibration signal, stratum identification, phase

中图分类号: 

• TP911.72