Studies On Detection Of Key Technique In Ground Penetrating Radar

The lossless detection technique is widely used in many fields of applications with its development. One of the untouched detection devices, namely ground penetrating radar (GPR), is an important to be used in practice. It possesses many properties than other routine, for instance resistance method, low frequency electromagnetic induction, seismic method, and so on. The properties are made up of fast detection, continuing detection, high resolution, convenient-flexible operation, low cost, wide detected range, and so forth. Therefore GPR is paid attention by people. It is a hot point to be studied that the signal processing of GPR belongs to a key technique in the system of GPR from internal to overseas. The signal processing of GPR includes many of problems, but imaging, detection and recognition about buried targets are important contents, and then they are discussed in the paper in detail.The paper studies GPR in the system. The detection and other associated techniques are done in GPR in detail. The paper presents a few of new techniques and realizes a theoretical sample of GPR based on the important parts of GPR. The studied work and innovative points are described in the paper as following.Firstly the paper proposes that a novel design method on layered uniform amplifier, which resolves the problem that deep signals of GPR are decayed. The method firstly takes many of measured lines that are averaged to obtain mean of echoes, and then both original-measured lines and averaged echoes are segmented, which is equal to make underground image layer. Secondly it determines uniform-magnified maximum based on maximum peak-peak value of echoes that is compared with the peak-peak value of averaged segments in echoes, and then the ratio is taken as uniform-magnified vector factor to original measured lines. Finally measured lines are operated with uniform-magnified vector factor by dot matrix to get layered-uniform imaging data. Therefore the method can enhance the signals in deep, and then computer technique is made full of imaging with real time to realize deep layer detection and improve resolution in GPR.Secondly the paper brings forward a new method of nonlinearly adaptive interpolation (NLAI) to overcome the limitation traditional fixed interpolation. NLAI firstly adopts slope of border upon nodes as its quadric derivative, which is acted as curvature determinant. So based the threshold of interpolated number, the characters of signal are obtained by pre-segment method in the algorithm. According to the nonlinear interpolation function, the algorithm optimizes segments to obtain optimal interpolation. Both the speed and effectiveness of the interpolation operation are improved by the NLAI. So the real-time echoes of GPR are observed better than without NLAI.Thirdly the paper puts forward an interesting area interpolation algorithm (IIA). IIA firstly structures a mode of the detected targets, and then adopts quadric statistic to detect the horizon position of the targets. Secondly it takes diamond templates to process measured lines that contain buried targets. Thirdly it detects the depth of buried targets by statistics. Fourthly IIA enhances the area of buried targets with the correlation. Finally it does double linear interpolation to magnify interesting area of targets, and then the results are imaged to obtain interesting area magnified and detailed. IIA overcomes the limitation of localizations by artificial detection and recognition. It is not effective that the traditional enhancing image techniques are adopted, for instance edge process, histogram enhancing image, and so on. The reason is that the gray level of imaging is few in GPR.Fourthly the paper presents a method that can locate buried three-dimension (3-D) targets automatically based on C-scan. The method is used to overcome the problem on 3-D targets automatically locating in GPR. It makes parallel filter groups eliminate direct arrival wave of A-scan with varied length. Then echoes are detected with matched wavelet to get its oddity, and then it simply determines buried targets whether or not. The detection method takes maximum mode based on statistics in multi-scale wavelet field. The suspicious positions are determined to decrease false alarm rate by space-time correlation method. Finally the positions of buried targets are obtained by local focus of synthetic aperture radar (SAR) on 3-D position.Fifthly the paper presents a method that recognizes 3-D buried targets based on both high-order spectra (HOS) distributing features and multi-feature recognition (MFR) method. Multi-features of GPR include the hyperbola in space-time along measured lines, the depth feature of 3-D buried targets, namely attenuation waves or varied scope of echoes, and correlation of buried targets in space. HOS possesses more properties than power spectrum, for example phase and frequency information. HOS is acted as the rule of recognized targets so that it is feasible in theory. Thus the response of incidence electromagnetic wave is mapped indirectly to the distributing of HOS on buried targets.Sixthly the theoretical sample of pulse ground penetrating radar without carrier is completed in the paper. The device is proved to detect buried targets by practical tests. The designed sample possesses key techniques that are ultra-wide antenna, narrow pulse resource and signal processor.