I always watch your videos. They either inform me of something new, or reinforce something I already knew. Sometimes, the video takes the info I already know, and tells me how to apply it. I knew I knew depth, dielectric, and target size. And I have in the past played with the orientation. Another great, informative video from the GPR Mastermind!
I am not convinced by #4 " In situations with faster wave velocities (such as in dry sand), a target will produce a broader hyperbola." Did the antenna beam width change?
Hey Caleb! You are a skeptical one for sure. I would suggest that if you are not convinced that velocity impacts hyperbola size/shape/angle (covering all my bases for you) then definitely DO NOT use hyperbola matching functions on any gpr or Post processing software to estimate depths/dielectric/velocity. This critical function which is the most common way to estimate velocity is based on the premise that faster velocities will produce broader hyperbola. It's why no system will allow a fit broader than air, since the wave moves at the speed of light, the fastest speed in the universe that we know of. However you bring up another good point which I may not have gone over in the video...it's been a while. In dry materials, the signal footprint will be larger (diameter), and in wet materials the signal footprint condenses. I made a video about this too. You should be able to find this on the channel. Again, thanks so much for the comments. I appreciate the question!
I started a PhD in GPR for landmine detection this year. I have started to try and estimate wave velocity and found your video :) Different size because of the distance away? Im imagining a receiver at infinity in the gpr trace would be a flat line. As you get closer the hyperbola gets sharper. Also target size and i guess shape to an extent. All would play a part. Now im imagining a receiver at infinity and an infinitesimal target size.. assuming no loss. We'd see a hyperbola again? So the hyperbola size is a function of both. Now same target size at a different site. One with infinite relative permitivitty, you'd get an indefinite delay. Reduce that and the hyperbola would start flat and sharpen again?
Interesting. I have not thought about that. I guess generally we consider that attenuation would happen, but in airbyou could extrapolate out to infinity in the horizontal plane which theoretically would flatten the curve. Thanks for the comment and the thought experiment.
@@Learngpr Thanks for the video :) i'll be watching some more today. I would have thought a slower wave would make a larger hyperbola, so that was counterintuitive for me. Very interesting!
Hi Dan, I’m quite new to GPR and your videos have helped me a lot in understanding GPR. I think that the, 1. Diameter/size of the object 2. Orientation of the week object 3. RDP of soil Could affect the hyperbola size
New to GPR and currently doing my BEng thesis on the use related to tree roots. what would you say is the best action to identify the hyperbola of tree roots. great video btw
excelente info,como aparece una hipérbola,cuando detecta un tanque grande de una estación de gasolina,y cuando son tanques rectangulares,pasando el gpr a 90°,como dices,que las hipérbolas dependen también de la profundida,el aparato aparece,la profundida,de la detección,se tendrá que recalibrar el equipo,,,saludos,,,
Great video Dan. I have a question slightly different to point 4. What if two targets of same size and shape but different material are buried in the same strata e.g. a 6" PVC pipe and a 6" Steel pipe both buried in same soil, so will this effect the size of hyperbola?
Hasan Shirazi it should not affect the size of the hyperbola. The effect of depth has to do with wave velocity and the velocity is calculated based on the average to the target. So the hyperbola should be the same size, but the amplitude of the reflections should differ between PVC and metal.
how does the permittivity affects the simulation sir? because i am working in hfss ..where i can analyze 4meter depth using marblr or silicon permittivities...but the moment i keep water as substrate we couldnt able to get 0.25m analysis why this is happening sir? we are analyzing gpr to detect ground water.
So the water more affects the conductivity. This is an issue because the electeical field of the gpr wave will decay quickly in more conductive material.
it seems to me that you forgot to say that hyperboles also come from ground objects that are far from the profile. But these objects generate huge hyperbolas, for example, pillars, corners of buildings or eucalyptus trees. and of course I completely agree that the geological environment is a very active zone for changing electrophysical properties.
Leonid K. Thanks for the comment Leo! I think i would classify the example of air waves as hyperbola differing in size because of speed. The wave moves fastest in air and always produces the broadest possible hyperbola for a given "depth". However, closer objects on the surface will be more narrow than those that are further away...so I guess distance could also account for it. Much appreciated as always!
OK, I'm game, have paused the video. First, the grammarian must point out that the plural of hyperbola is hyperbolas or hyperbolae, according to Merriam-Webster (hey, you used "are"). One reason they can be different sizes is if you are not perpendicular on approach. Another is if the dielectric is different. Of course, if the object itself is wide and flat at the top, that will widen the hyperbola but not the tail (depends on what you mean by "size"). You also have a video that warns about hyperbolae that are due to air reflections (which is kind of the same thing as different dielectrics). Now let me watch your video and see if there's another one I've missed...
I use antennas that are tightly coupled to the surface, so the hyperbolas basically keep going down to the bottom of the radargram (unless they are interrupted by other objects), no matter how deep they are. On the other hand, the gain curve makes lower hyperbolas much thicker than hyperbolas closer to the surface, which is definitely a difference in size, so I'll agree. Great video, Daniel!
bdrogin thanks Barry! Grammatical correction well taken. I appreciate you playing. 3 out of 4 is good. I known that "size" is kind of vague. Great point about thickness. I didn't take that into consideration.
I always watch your videos. They either inform me of something new, or reinforce something I already knew. Sometimes, the video takes the info I already know, and tells me how to apply it.
I knew I knew depth, dielectric, and target size. And I have in the past played with the orientation.
Another great, informative video from the GPR Mastermind!
Thanks so much Joe! I always appreciate your support!
This video is so helpful for beginners. Thank you!!!
@@arkjn20 you are so welcome! Thanks for the comment!
This video was super helpful!! Thank you 🙌🏻
Thank you so much! Glad it was useful.
I am not convinced by #4 " In situations with faster wave velocities (such as in dry sand), a target will produce a broader hyperbola." Did the antenna beam width change?
Hey Caleb! You are a skeptical one for sure. I would suggest that if you are not convinced that velocity impacts hyperbola size/shape/angle (covering all my bases for you) then definitely DO NOT use hyperbola matching functions on any gpr or Post processing software to estimate depths/dielectric/velocity. This critical function which is the most common way to estimate velocity is based on the premise that faster velocities will produce broader hyperbola. It's why no system will allow a fit broader than air, since the wave moves at the speed of light, the fastest speed in the universe that we know of.
However you bring up another good point which I may not have gone over in the video...it's been a while. In dry materials, the signal footprint will be larger (diameter), and in wet materials the signal footprint condenses. I made a video about this too. You should be able to find this on the channel.
Again, thanks so much for the comments. I appreciate the question!
I started a PhD in GPR for landmine detection this year. I have started to try and estimate wave velocity and found your video :)
Different size because of the distance away? Im imagining a receiver at infinity in the gpr trace would be a flat line. As you get closer the hyperbola gets sharper.
Also target size and i guess shape to an extent. All would play a part.
Now im imagining a receiver at infinity and an infinitesimal target size.. assuming no loss. We'd see a hyperbola again? So the hyperbola size is a function of both.
Now same target size at a different site. One with infinite relative permitivitty, you'd get an indefinite delay. Reduce that and the hyperbola would start flat and sharpen again?
Interesting. I have not thought about that. I guess generally we consider that attenuation would happen, but in airbyou could extrapolate out to infinity in the horizontal plane which theoretically would flatten the curve. Thanks for the comment and the thought experiment.
@@Learngpr Thanks for the video :) i'll be watching some more today. I would have thought a slower wave would make a larger hyperbola, so that was counterintuitive for me. Very interesting!
HI dan. Really appreciate if you could explain to me more on the orientation of 0 degree. Why do the hyperbola become flat?
Hi Dan, I’m quite new to GPR and your videos have helped me a lot in understanding GPR.
I think that the,
1. Diameter/size of the object
2. Orientation of the week object
3. RDP of soil
Could affect the hyperbola size
These are all correct! Great job. The only other would be depth. Thanks for watching and I'm glad you are finding them helpful.
New to GPR and currently doing my BEng thesis on the use related to tree roots. what would you say is the best action to identify the hyperbola of tree roots.
great video btw
Hi, I answered you in the other post. We would use gpr slice to create visuals.
excelente info,como aparece una hipérbola,cuando detecta un tanque grande de una estación de gasolina,y cuando son tanques rectangulares,pasando el gpr a 90°,como dices,que las hipérbolas dependen también de la profundida,el aparato aparece,la profundida,de la detección,se tendrá que recalibrar el equipo,,,saludos,,,
Hello sir. Do you think that PhD disertation is possible using georadar? Can you please give an opinion on what subject could be researched. Thanks!
Bad ideas
@АлександрМельников-в8л why
Hi Dan, can the size of the pipe be determined with GPR? Thanks for the videos
Hi Frank. Unfortunately it is not an accurate method for pipe diameter estimates. Rebar, debatable, but utilities have more variables.
Great video Dan. I have a question slightly different to point 4. What if two targets of same size and shape but different material are buried in the same strata e.g. a 6" PVC pipe and a 6" Steel pipe both buried in same soil, so will this effect the size of hyperbola?
Hasan Shirazi it should not affect the size of the hyperbola. The effect of depth has to do with wave velocity and the velocity is calculated based on the average to the target. So the hyperbola should be the same size, but the amplitude of the reflections should differ between PVC and metal.
how does the permittivity affects the simulation sir? because i am working in hfss ..where i can analyze 4meter depth using marblr or silicon permittivities...but the moment i keep water as substrate we couldnt able to get 0.25m analysis why this is happening sir?
we are analyzing gpr to detect ground water.
So the water more affects the conductivity. This is an issue because the electeical field of the gpr wave will decay quickly in more conductive material.
In mediums with higher DC, like clay, the beam width of the antenna is narrower leading to smaller hyperbolas and vice versa!
Very true! Footprint matters a lot. Thanks for the comment.
Hello professor
1-RDP
2-size of pipe
3-polarity
4- I don't know
:)
Good try!
it seems to me that you forgot to say that hyperboles also come from ground objects that are far from the profile. But these objects generate huge hyperbolas, for example, pillars, corners of buildings or eucalyptus trees. and of course I completely agree that the geological environment is a very active zone for changing electrophysical properties.
Leonid K. Thanks for the comment Leo! I think i would classify the example of air waves as hyperbola differing in size because of speed. The wave moves fastest in air and always produces the broadest possible hyperbola for a given "depth". However, closer objects on the surface will be more narrow than those that are further away...so I guess distance could also account for it. Much appreciated as always!
G
Easy to understand, awesome, tq
Thanks!
thanks sir
Sahil Tikku you are welcome!! 😉
OK, I'm game, have paused the video. First, the grammarian must point out that the plural of hyperbola is hyperbolas or hyperbolae, according to Merriam-Webster (hey, you used "are"). One reason they can be different sizes is if you are not perpendicular on approach. Another is if the dielectric is different. Of course, if the object itself is wide and flat at the top, that will widen the hyperbola but not the tail (depends on what you mean by "size"). You also have a video that warns about hyperbolae that are due to air reflections (which is kind of the same thing as different dielectrics). Now let me watch your video and see if there's another one I've missed...
I use antennas that are tightly coupled to the surface, so the hyperbolas basically keep going down to the bottom of the radargram (unless they are interrupted by other objects), no matter how deep they are. On the other hand, the gain curve makes lower hyperbolas much thicker than hyperbolas closer to the surface, which is definitely a difference in size, so I'll agree. Great video, Daniel!
bdrogin thanks Barry! Grammatical correction well taken. I appreciate you playing. 3 out of 4 is good. I known that "size" is kind of vague. Great point about thickness. I didn't take that into consideration.
Not interesting system GPR. Bed resolution, so many mistakes