低频地质雷达屏蔽天线开发及在地下空间工程探测应用

Development of low-frequency GPR shielding antenna and its application in underground space engineering detection

地质雷达技术已经广泛应用于地质结构及安全隐患探测中,受限于复杂地质条件,常规地质雷达探测天线系统存在探测深度浅、深部探测精度降低等缺陷,且难以实现实时处理功能。开发了一种低频地质雷达屏蔽天线系统,与常规地质雷达天线系统相比,该系统有2个优势:①通过低频屏蔽及阻抗匹配设计,增强了天线的聚焦和辐射特性,可有效屏蔽环境干扰信号,提高数据的信噪比;②构建了基于FPGA的数据实时处理框架,应用于可编程芯片上,系统开发实现了数据内插、去噪、增益等处理算法的集成,实现了数据的实时处理。试验结果表明:该低频地质雷达天线系统在城市环境下其探测深度可达30 m,基于FPGA的处理模块实现了数据的实时处理,同时数字图像实时处理算法将图像信息熵、平均梯度等相对常规数据的处理平均提升分别为13.72%、12.44%。

Ground penetrating radar(GPR) technology has been widely used in the detection of geological structure and potential safety hazards. Limited by complex geological conditions, the conventional GPR detection antenna system has some defects, such as shallow detection depth and reduced deep detection accuracy, and it is difficult to realize real-time processing function. Compared with the conventional GPR antenna system, the developed low-frequency GPR shielding antenna system in this paper has two characteristics:①Through the low-frequency shielding and impedance matching design, the focusing and radiation characteristics of the antenna are enhanced, which can effectively shield environmental interference signals and improve the signal-to-noise ratio of data;②A real-time data processing framework based on FPGA is proposed, and the integration of data interpolation, denoising, gain and other processing algorithms is realized by the application of programmable on-chip development, realizing real-time processing. The test results show that the detection depth of the low-frequency GPR antenna system can reach 30 m in the urban environment. The FPGA-based processing module realizes the real-time processing of the data, and the digital image real-time processing algorithm can improve the processing of relative conventional data, such as the image information entropy and the average gradient are increased by 13.72% and 12.44% on average.