In utility mapping applications, 3-D GPR is used to scan and map underground features, performing deep surveillance beyond the reach of visual inspection to obtain data critical to construction and utility management. The use of 3-D GPR in road inspection typically involves measurements of asphalt thickness, base layers, instabilities, deformations and damage. In the United States, approximately $40 billion is spent annually on road maintenance, and some estimates suggest a potential 10 percent savings can be derived from using imaging methods on a large scale.
Until recently, 3-D GPR systems have required traveling over the same ground area in multiple passes with multiple antennas to capture the necessary data and create the 3-D image. A better approach involves the use of SF GPR, which was conceived at the Norwegian University of Science and Technology approximately 10 years ago.
SF GPR operates at 100 MHz to 3 GHz, with a penetration of 2 to 3 meters, and eliminates the need for covering the same area of ground with multiple antennas to obtain the necessary data. The SF GPR antenna array enables a single swath or pass to produce the desired three-dimensional data cube. The time savings over traditional GPR is significant. In the case of a ground survey for an archaeological project, a traditional impulse radar system required four weeks to survey a 4-hectare area; an SF GPR survey of the same density grid was obtained in a single week.
|The electronically scanning antenna array allows efficient and accurate three-dimensional data acquisition for applications such as IED detection; utility mapping; and road, railway and airfield inspection.|
The traditional approach to GPR, commonly used in the commercial domain, is for data to be collected and then processed and analyzed afterward, with a typical ratio of three days of analysis for each day spent collecting data, after which a couple of weeks may be spent writing up a report based on the data. One of the advantages of SF GPR is that it enables visual analysis of underground structures in real-time. Thus, on-the-spot discovery of an object of interest can immediately influence the data collection process.
The traditional approach requires waiting until after data is analyzed to determine where and how to narrow the focus of analysis. With SF GPR, once an object of interest is located, the vehicle can literally be backed up to conduct further interrogation and a more detailed survey.