Time delay and interface roughness estimations by GPR for pavement survey

Abstract

In civil engineering, ground‐penetrating radar is widely used for road pavement surveys. In contrast to the existing literature, this paper takes account of the influence of interface roughness (surface and interlayer roughness) within the scope of data processing of radar signals. The rigorous electromagnetic method PILE (Propagation Inside Layer Expansion) provides simulated data that show the influence of the interface roughness on the backscattered primary echoes of stratified media; the interface roughness provides a continuous frequency decay of the magnitude of the echoes. The observed frequency variations of the radar magnitude introduce some shape distortion on the radar waveform. The latter variations can be modelled by an exponential function, which provides satisfactory results for a narrow bandwidth (2 GHz). An adaptation of the root‐MUSIC algorithm is proposed. As a result, it is possible to jointly estimate the time delay and the interface roughness. The algorithm is tested on data simulated by the PILE method and numerical examples are provided to assess the performance of this algorithm. The associated results show that the proposed algorithm can estimate both the time delay and roughness parameters with a small relative error.

Time-Delay Estimation by a Modified Orthogonal Matching Pursuit Method for Rough Pavement

“…In the case of narrow frequency bands, namely less than 2 GHz, the frequency behavior of the backscattered echoes coming from interface roughness can be approximated as an exponential function [15]. High-resolution methods like MUSIC and ESPRIT combined with spatial smoothing-based techniques can easily be adapted for estimating the pavement parameters like layer thickness, permittivity, and interface roughness [17], [18]. However, the assumption of the exponential function is not valid with the widening of the frequency bandwidth [15].…”