This information can be used to determine the depth to- and geometry and magnitude of subsurface reflectors. The amplitude variations and wave velocity-dependent travel time of the returning signal are measured and recorded by the GPR receiver. If a wave pulse encounters a material interface of sufficiently different electromagnetic properties, some of the energy is reflected back while the remainder continues to propagate. GPR capitalizes on the effects that the electrical properties of matter (i.e., dielectric permittivity, electrical conductivity, and magnetic permeability) have on electromagnetic (EM) energy propagation. I did find at least one GPR vendor asserting that operation of a GPR was limited to no more than 1 meter above ground, but I was unable to determine how they came to this conclusion.Ground penetrating radar (GPR) is an electromagnetic geophysical method that transmits radio wave pulses at select center frequencies into the ground to study the subsurface. u/Gladstonetruly Would you mind citing the ruling on which you are basing your statement? I looked over 47 CFR 15 and I don't see anything which explicitly forbids mounting or operating GPR systems on aerial platforms. The height at which it will work well depends on the frequency used by the GPR system. It seems GPR works best when in contact with the surface, though above-ground operation is not impossible. GPR vendors who address the matter suggest keeping within a couple feet (literally, two feet) of the surface. In general, the higher up your GPR antenna sits, the harder it is to get good results, due to energy reflection from the surface. It seems the biggest challenge to drone-based GPR is getting quality scan results. Those I found which showed a price were in excess of $10k for the GPR unit (and possibly the required software and training, it was not clear in all cases) and go up from there - including bundles which provided a GPR unit and a drone (again, possibly including software, training, etc.). There's not a lot of product offerings, and pricing usually involves contacting the vendor. This was an interesting idea, so I did some reading. Not trying to poop on your parade by any means, but I do think your expectations of the technology are a bit too high. But those are already surveyed in before they are buried by law. The only uses I can fathom for such a task would be pipeline locating. Seeing as that is pretty impractical, it would be more so a case where you are locating a line that is 36-48" in diameter at a depth of 5-10' below ground. The only thing you are going to be able to reliably locate is a 20" line running just below the surface of the ground. By that logic if you are flying a drone at 20 feet from the ground. For example, a 2" utility can only be reliably located at a distance from the antenna of no more than 2 feet. Worth mentioning, those systems are used mainly for rough geoscience exploration, rather than utility location.įor utility location, a good rule of thumb is that for every 1 foot of depth that an object is away from the antenna (which is usually it's depth of cover as the antenna is on the ground surface) said utility must be 1" in diameter. Don't get me wrong, they are out there, but the systems that actually work are in the 7-8 figure range, and they mount to airplanes, not drones. That said, I think you will have a hard time finding a system that will work when mounted to an aerial platform. I do not consider myself to be an expert on GPR by any stretch, but I do sell underground utility locating equipment for a living and have a pretty good understanding of its limitations. Gotcha, no you are correct, GPR is what you are looking for, as LiDAR will not work in that situation.
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