Su Yi

A new GPR calibration method for high accuracy thickness and permittivity measurement of multi-layered pavement

To improve the measurement accuracy for the layer thickness and the permittivity of multi-layered pavement, this paper proposes a new calibration method. Based on the layerstripping EM inversion, single or two calibrating coefficients are introduced into the calculation equations of thickness and permittivity. After the processing of calibration the nonlinear meaisurement errors. can be diminished effectively, and the accuracy of overlaid delamination can be improved. Moreover, the affection of calibration factors is discussed, and a lot of pavement data have been used to test and prove the performance of the calibration methods.To improve the measurement accuracy for the layer thickness and the permittivity of multi-layered pavement, this paper proposes a new calibration method. Based on the layer-stripping EM inversion, single or two calibrating coefficients are introduced into the calculation equations of thickness and permittivity. After the processing of calibration the nonlinear measurement errors can be diminished effectively, and the accuracy of overlaid delamination can be improved. Moreover, the affection of calibration factors is discussed, and a lot of pavement data have been used to test and prove the performance of the calibration methods. Keywords-calibration; thickness; permittivity; measurement; GPR; multi-layered pavement; high accuracy

A real-time back projection imaging algorithm for impulse surface penetrating radar

A real-time recursive back projection (BP) imaging algorithm is presented in this paper. Real time imaging is an intense demand but a challenging task in impulse surface penetrating radar (ImpSPR)s application. Based on delay-sum operation in time domain, BP imaging algorithm can precisely focus the scattering intensity and obtain high quality subsurface profile. But its heavy computation burden restricts its application in ImpSPRs real-time processing. By minutely analyzing its procedure, a recursive model of BP imaging algorithm is established and real-time BP imaging algorithm is educed subsequently. The computation complexity of both non real time BP imaging algorithm and real time BP imaging algorithm are analyzed. Through processing the experimental data obtained by a ImpSPR system- RadarEye, the imaging algorithm validates its capability at the aspect of ImpSPRs real time processing.

Ultrawideband radar signal detection, estimation, and experiment

With reference to the air target detection of ultra- wideband(UWB)/impulse radar, we discussed transient signal processing techniques. In weak UWB signal detection, wavelet transforms and high order spectrum estimation techniques were preferred. In target characteristic analysis, two algorithms of impulse response deconvolution, MCGM and DPREM, were presented. In this paper, a time domain bispectrum estimation algorithm was used to analyze target impulse response, which could estimate accurately local scattering distribution of complex target. A free field IR experimental system was used which was laid out in an anechoic chamber. With this system, we measured the response of several target models and a scale aircraft.

Simulation of SAR image of ship

Simulation of SAR (Synthetic Aperture Radar) image of ship is very important for ship detection and classification of airborne and space-borne SAR platforms. Based on the research of high frequency RCS (Radar Cross Section) prediction, the methods of SAR image simulation of ship are investigated in this paper. First, a triangle-facet model of a ship is modeled using 3D Studio MAX, then the RCS of the ship is computed using the combination of PO (Physical Optics) and PTD (Physical Theory of Diffraction), finally, with SAR image formation processing, the predicted complex scattered field is turned into the SAR image of the ship. The validity of high frequency RCS prediction is verified through the RCS prediction result of a rectangular plate, and the validity of SAR image simulation of ship is verified through the simulated SAR images of a simple geometry structure made of four rectangular plates and a real ship model. Keywords-SAR; ship; simulation

Sequential discrimination with multi-features to remove false ROIs in SAR ATR

Because the prescreening usually adopts an anomaly detection approach to highlight the vehicle-targets in SAR image, many false regions of interest (ROIs) are produced to reduce hardly the efficiency of the ATR. A new method based on sequential discrimination with multi-features is proposed to remove these false ROIs in this paper. By quantitatively analyzing the redundancy, robustness and separability of the candidates, the optimal features are selected to form an orderly vector, which is compared with the vector of threshold to finish a sequential discrimination. The performance of the above algorithm is validated by the X band MSTAR data, and is compared with the quadratic distance discriminating (QDD) method.

Optimization based underground cylindrical objects position and electromagnetic parameters joint reversion

In the applications of surface penetrating radar(SPR), the localization and recognition of cylindrical objects such as conduits and cavities is a typical problem. To obtain high accuracy subsurface profile, wide band signals are adopted in SPR system. Thus the problem of subsurface point objects’ location can be implemented by maximum likelihood parametric algorithm in the frequency domain. Subsurface objects recognition is a challenging task. Based on feature extraction and judgment, it needs adequate typical subsurface objects’ feature. In this paper, a novel method of optimization based joint reversion is presented. Based on the first order Born approximation, the relationship between receiving signals at each aperture and the objects’ position, electromagnetic parameters is established and maximum likelihood parametric algorithm is introduced to estimate unknown parameters. Through processing experimental data obtained by a SPR system-RadarEye, the maximum likelihood parametric algorithm validates its capability at the aspect of subsurface cylindrical objects’ position and electromagnetic parameters joint reversion. Keywordssurface penetrating radar; object localization; object recognition; maximum-likelihood estimation