On the Application of Multi-frequency Ground-Penetrating Radar Method for Mapping Underground Pipe

Abstract

Ground penetrating radar (GPR) method is commonly used to map underground pipe network due to its ability to map objects on shallow area and its minimum effect to surrounding area, although the resolution and depth of interest of mapping really depend on the antenna's frequency. To improve the resolution of object that is going to be detected, more than one antenna frequencies are used in a measurement in the same line and multiple-frequency compositing is performed to combine those radargrams to simplify the analysis. This research will use and compare three compositing methods ability, i.e. simple summation, comparison of average radargram amplitude spectrum of each radargram, and least-square weighting according to Berlage wavelet analysis - called also Optimal Spectral Whitening (OSW), to map a big pipe with metal casing that surrounded with some metal cables from 200 MHz and 400 MHz radargram datasets. Comparisons of those three methods mentioned above were performed through the analysis of each radargram and sample trace analysis on some positions to show the ability of each method in separating boundary of each medium. The analysis showed that multiple-frequency compositing was able to improve resolution for showing underground condition, with OSW method had better ability compared to other methods.