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Overview Objective: Estimation of geo-physical parameters from Ground

Courtesy: JPL, NASA. Weaker returns cannot be resolved. Weaker returns are resolved. Model Based Signal Processing for GPR Data Inversion. MUSIC Algorithm. Overview Objective: Estimation of geo-physical parameters from Ground

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Overview Objective: Estimation of geo-physical parameters from Ground

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  1. Courtesy: JPL, NASA Weaker returns cannot be resolved Weaker returns are resolved Model Based Signal Processing for GPR Data Inversion MUSIC Algorithm Overview Objective: Estimation of geo-physical parameters from Ground Penetrating Radar (GPR) data – also called Electro- Magnetic (EM) Inversion Principle: Permittivity contrast in layered media causes reflection of incident Electromagnetic Wave • MUSIC : MUltipleSIgnalClassification • Super resolution frequency estimation technique • Exploits Orthogonality of signal and noise • Enhances valid returns and suppresses noise peaks • Requires reliable propagation model Simulations Geo-Physical Profile PermittivityProfile Radar System Reconstructed Vs actual Permittivity profile Range profiles obtained using FFT & MUSIC A typical dielectric profile Inversion Techniques Inversion on Actual Radar Data • Layer Stripping Technique • Apply Fourier/Inverse Fourier Transform on received signal • Set threshold and locate position and amplitudes of interfaces • Reflection amplitudes and time delays are related to permittivity • Recursively estimate permittivity profile • Wide Band FMCW Radar (2 – 8 GHz) used in Antarctica to estimate snow thickness • MUSIC algorithm was used for enhancement and permittivity estimation • Core data was modeled into permittivity profile using theoretical models • Problem of False alarms and missed peaks • Weaker returns are buried under side-lobes of stronger returns Model Based Inversion • Based on MMSE Minimization: Gauss Newton Method Based on Spectral Estimation: MUSIC Algorithm . Convergence issues – produces unstable/un-useful solutions . Problem with depth discretization . Requires good SNR Works best ! Reconstructed Vs actual permittivity profile Range profiles obtained using FFT & MUSIC GUI for the inversion algorithm 040105

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