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利时用合成孔径聚焦技术(SAFT)检测混凝土缺陷,常规的短脉冲检测方法信噪比较低,导致检测距离较浅,使应用范围受到限制。本文引入雷达探测中使用的脉冲压缩技术,并提出了改进的基于脉冲压缩技术的合成孔径聚焦榆测方法(ISAFT)。该方法通过发射线性调频信号(LFM),将缺陷回波信号经匹配滤波进行脉冲压缩处理,得到的压缩信号具有主瓣宽度较窄、峰值较高的特点。然后利用该压缩信号进行SAFT成像处理,提高了图像对比度。与常规的短脉冲检测方法相比,该方法既提高了信噪比,又保证了缺陷检测的分辨率。理论和实验结果表明,该方法不仅能抑制噪声提高成像对比度,而且还适用于混凝土内部多个缺陷的检测。
When using synthetic aperture focusing technology (SAFT) to detect concrete defects, the conventional short pulse detection method has a low signal-to-noise ratio, which results in a shallow detection range and limited application range. In this paper, the pulse compression technique used in radar detection is introduced and an improved method based on pulse compression is proposed. In this method, the LFM signal is transmitted, and the defect echo signal is subjected to pulse compression processing by matched filtering. The obtained compressed signal has the characteristics of narrower main lobe and higher peak value. Then use the compressed signal SAFT imaging processing, improve the image contrast. Compared with the conventional short pulse detection method, this method not only improves signal-to-noise ratio, but also ensures the resolution of defect detection. Theoretical and experimental results show that this method can not only suppress the noise to improve the imaging contrast, but also apply to the detection of multiple defects in concrete.