Traffic-speed 3-D noise modulated ground penetrating radar (NM-GPR)

A new type of high-performance ground penetrating radar is presented based on a variant of the noise-modulation technique. Benefits of the approach include high operational efficiency; simplified and more robust electronics; stable performance; compatibility with a wide range of antenna types and better compliance with regulatory emission restrictions. A prototype NM-GPR system has been in operation since 2008, tailored to road pavement investigations. That system consists of 24 radar channels in a 3-D configuration with arrays of ground coupled antennas. Each radar channel can operate simultaneously, collecting a 256 point GPR trace every 65mm at a collection speed of 100 kilometers per hour. This equipment has been used extensively within Australia for road investigations. To date more than 100 projects totaling over 5,000 lane-kilometers of road scanning have been completed with the prototype, producing excellent results. The resolution of data produced with the current antennas is similar to commercial 1.5GHz ground coupled impulse system, but with a typical penetration depth of around one metre for most Australian road pavements. This paper describes this new approach to GPR hardware and its use to date for investigating Australian road pavements.