Sublayer-thickness inversion of asphalt layer from ground penetrating radar data

A new technique for measuring the permittivity and sublayer thickness of asphalt layer from air-launched ground penetrating radar (GPR) data is presented. This technique involves three major steps: (1) estimation of the time delay of echoes by means of independent component analysis, (2) determination of the permittivity of each sublayer by pattern search method and (3) calculation of the thickness of the individual layers. Numerical simulations show that the overlapped GPR echoes can be separated even if the surface sublayer is quite thin and the low dielectric contrast between sublayers is present. Analysis of field test data of a commonly used impulse GPR is introduced.