Share Email Print

Proceedings Paper

Pavement thickness measurement using FM-CW radar
Author(s): C. Richard Liu; Jing Li; Xinhua Gan; Huichuan Xing; Xuemin Chen
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Many theoretical studies have been reported on applications of ground penetrating radar (GPR) system to detect the permittivity and thickness of subsurface layers. However, to develop a GPR system that can accurately measure the thickness and the permittivity simultaneously is not a straightforward task. The main difficulty of quantitative thickness measurement is that the reflected wave from the subsurface interface is very weak compared to the directly coupled waves. The reflected signal may be completely submerged into the strong direct waves. Secondly, the inversion computation from measured data is very noise sensitive. In this paper, we present the development of a frequency-modulated-continuous-wave (FMCW) radar for quantitative layer thickness measurement. A new mathematical model for the calculation of depth and permittivity from the measured electromagnetic data is presented. The new model is based on the time delay between the direct wave and the reflected wave recorded by a bistatic radar. The data inversion algorithm considers the influences from air-ground interface. It is found that neglecting the air layer effects as the case applied in seismic analysis, the inversion will not be correct. This is because the electromagnetic rays from the GPR take different propagation path from straight or curved ray in seismic-like analysis. Ray path searching must be included in the calculation algorithm. With the consideration of wave path, the experimental results agree well with the actual values either in field test of in laboratory test.

Paper Details

Date Published: 27 November 2001
PDF: 8 pages
Proc. SPIE 4491, Subsurface and Surface Sensing Technologies and Applications III, (27 November 2001); doi: 10.1117/12.450157
Show Author Affiliations
C. Richard Liu, Univ. of Houston (United States)
Jing Li, Univ. of Houston (United States)
Xinhua Gan, Univ. of Houston (United States)
Huichuan Xing, Univ. of Houston (United States)
Xuemin Chen, Univ. of Houston (United States)

Published in SPIE Proceedings Vol. 4491:
Subsurface and Surface Sensing Technologies and Applications III
Cam Nguyen, Editor(s)

© SPIE. Terms of Use
Back to Top