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Title:: Research on Time-frequency Analysis and Attributes Extraction of Air-gun Signal Based on HHT

Author(s):: ZHENG Lulu; LIN Jianmin; PANG Lichen; ZHU Hanhao; (School of Marine Science and Technology,Zhejiang Ocean University, Zhoushan 316022, Zhejiang, China)

Keywords:: Hilbert-Huang transform; air-gun source; high-frequency pressure pulse; low-frequency bubble pulse

摘要:: 通过Hilbert-Huang变换对浅水环境下气枪震源激发子波特征进行了研究,结果表明:气枪震源首先激发高频压力脉冲,其频带相对较宽,优势频率为40～80 Hz,主频随时间降低; 随后高压气体在水下形成的气泡振荡激发低频气泡脉动,其频带相对较窄,优势频率为4～12 Hz,且水深较浅处的气泡振荡激发的气泡脉动主频相对较低。研究结果有助于提高对浅水环境下气枪震源激发的复杂近场信号的认识。

Abstract:: The characteristics of wavelet excited by the air-gun source in shallow water was studied by using the Hilbert-Huang transform. The results indicate that: firstly, the high frequency pressure signal which was excited by the air-gun of pressure pulse has the characteristic of broad frequency band,and dominant frequency with 40～80 Hz, and the primary frequency decreases with time. Then the low frequency bubble pulse which was excited by bubble oscillation induced by high pressure gas in underwater had the characteristic of narrow frequency band,the dominant frequency with 4～12 Hz, and the main frequency of bubble pulse excited by the bubble oscillation was relatively low in shallower water. The obtained study results will contribute to understanding the complicated near-field air-gun signal in shallow water.