摘要
针对超声混凝土缺陷检测信噪比低、穿透深度浅的问题,提出利用线性调频(LFM)信号检测混凝土缺陷。通过在发射端发射时宽和带宽的积大于1的LFM信号,在接收端将回波脉冲压缩,得到主瓣较窄,信噪比较高的压缩信号。理论分析了换能器带宽对压缩效果的影响。数值计算结果表明,在一定幅度的噪声存在条件下,回波信号经过脉冲压缩后仍能够得到好的压缩效果。实际检测结果表明,压缩后的LFM信号较压缩前检测信号明显提高了信噪比。
On account of existing problems of ultrasonic inspecting concrete defect, such as low signal noise ratio （SNR） and limited penetrating depth, the method of exciting with LFM is put forward. Linear frequency modulation （LFM） signal with the characteristics of long time series and wide band width is excited at transmitting terminal, and compressed signal with narrower main lobe and higher SNR will be obtained at receiving terminal through compression method. The effect of transducer＇s bandwidth is analyzed. The results of numerical calculation show that good compressed results of echo will be obtained if there is much noise. Testing results show that pulse compression method can improve signal-noise ratio.
出处
《CT理论与应用研究（中英文）》
2014年第1期19-26,共8页
Computerized Tomography Theory and Applications
基金
国家自然科学基金(11074273
41104117)
水利部行业公益性(201301061)
