Ground Penetrating Radar (GPR) is a technique where an ultra wideband electromagnetic signal is transmitted into the ground and the returned reflections measured to determine the presence of subsurface objects or features. For road pavements, GPR is used for locating and measuring:
- Pavement layer depths - asphalt, granular, and concrete.
- "As constructed" information and pavement changes / homogeneity.
- Anomalies - e.g. voids, rock, and buried objects.
- Moisture ingress and inclusions
- Calibrating deflection measurements to determine pavement material properties.
The PaveScout patented NM-GPR system, is unique. There is no other system in the world that has high real sample rate receivers in the one system (46 profiles across the 2.5 meter width of the system), which enables full 3D imaging of the road subsurface at 100km/h. There is no other system that can see as deep as 1.2 meters at 100km/h on all of the antennas, all at the same time. There is no other system that also performs common midpoint (CMP) dielectric compensation at the same time as data collection allowing calibration of subsurface layer depths and estimation of moisture within pavement layers. There is no other system that has been customized to reliability operate in difficult road conditions.
The 3D GPR system comprises of a trailer/antenna system, which then houses three GPR modules. The GPR modules are housed within the trailer, while the antennas, are housed within the radar pods. Each pod houses two transmitters and 5 receivers. There are three stages of protection, allowing reliable operation of the ground coupled antennas on the road surface.
- Each pod has 4 high speed wheels, with rims made from milled aluminium and heavy duty tread, allowing the antennas to glide over the road surface.
- The antennas have a thick 10mm replaceable nylon skid plate to protect the antenna from the road surface. Grooves on the skid plate indicate plate wear. The nylon skid plates are designed to be low cost, and easy to replace. Expected life of a skid plate is around 5000km (depending on road conditions).
- Finally each pod is individually suspended, with a tuned air ride suspension system, allowing the unit to move out of the way of larger object, while still hug the road surface.
When in operation the pods automatically deploy down onto the road surface, via a rugged motor/gearbox system. All elements of the system are designed with rough roads in mind. The RPS radar system is designed to last.
The 3D Ground Penetrating Radar (GPR) system is comprised of four electronically deployable pods. The results of the transmitters and receivers for the system are combined to produce a 46 wide antenna array. The result is a very high density 3D array image, with a data density of 50mm across the road, and 50mm along the road, down to a depth of 1.2 meters, all at 100km/h.
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