Signal Processing of Ground Penetrating Radar Using Spectral Estimation Techniques to Estimate the Position of Buried Ta

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Signal Processing of Ground Penetrating Radar Using Spectral Estimation Techniques to Estimate the Position of Buried Targets Shanker Man Shrestha Arai Laboratory, Electronic Engineering Department, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan Email: [email protected]

Ikuo Arai Arai Laboratory, Electronic Engineering Department, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan Email: [email protected] Received 29 March 2003 and in revised form 28 June 2003 Super-resolution is very important for the signal processing of GPR (ground penetration radar) to resolve closely buried targets. However, it is not easy to get high resolution as GPR signals are very weak and enveloped by the noise. The MUSIC (multiple signal classification) algorithm, which is well known for its super-resolution capacity, has been implemented for signal and image processing of GPR. In addition, conventional spectral estimation technique, FFT (fast Fourier transform), has also been implemented for high-precision receiving signal level. In this paper, we propose CPM (combined processing method), which combines time domain response of MUSIC algorithm and conventional IFFT (inverse fast Fourier transform) to obtain a super-resolution and high-precision signal level. In order to support the proposal, detailed simulation was performed analyzing SNR (signal-to-noise ratio). Moreover, a field experiment at a research field and a laboratory experiment at the University of Electro-Communications, Tokyo, were also performed for thorough investigation and supported the proposed method. All the simulation and experimental results are presented. Keywords and phrases: FFT, GPR, MUSIC algorithm, SFCW radar, super-resolution signal processing.

1.

INTRODUCTION

Spectral estimation techniques have been approved as a unique tool for signal and image processing of radar. There are different spectral estimation techniques, in which conventional fast Fourier transform (FFT) has been widely used for real-time measurement due to higher-computational efficiency and its ability to produce high-precision receiving signal level for a large class of signal processes. However, there are several inherent performance limitations of the inverse fast Fourier transform (IFFT) approach like low-frequency range, that is, its ability to distinguish the spectral response of two or more signals is very low, and implicit windowing of the data, that is, energy of the main lobe of a spectral response leaks into the side lobes. Generally, ground penetration radar (GPR) is a narrow bandwidth device and its radar range is normally high, a wide bandwidth is greatly desired to enclose all target images, which is difficult to make because it is limited by antenna size

in the low-frequency range and underground propagation characteristics in the high-frequency range [1, 2]. In order to overcome these problems, improvement of frequency resolution is greatly desired. Moreover, improvement of resolution