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PostPosted: Thu Apr 01, 2010 1:45 pm 
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Posts: 2
Thanks a lot for respons.

I was writing to Reinaldo as he knows for sure better this soft than me.
But I'm open for all constructive answers and everything what is connected with this subject.
Thanks for processed data and what do you think about them? Comparing to yours are they similar?
I thought that is possible to get much clearer picture ;(

1. I'm not satisfied with the end from the soft we've got so i'm looking for something better.
According to your excel file "freqwave" the wavelenght for 400MHz antenna is 75cm assuming that propagation is in the air.
But usually the wave is propagating in the ground (when the antenna is in contact with ground) where the velocity is around 10cm/ns, so in that case the wavelenght is three times less = 25cm. Using antenna on the railway 2,5cm above the ground is rather impossible

2. In acquisition soft is gain application that works only during acquisition for displaying data. After you copy data to processing soft it looks always exactly like that and there is no possibility to change it. I know it's strange

3. That's the way I performed survey.If I understood you properly. You mean to set the antenna perpendicular to the direction of survey.
Is it possible to see your results from railway?

Happy Easter


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PostPosted: Thu Apr 01, 2010 2:46 pm 
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Joined: Wed Apr 29, 2009 5:52 am
Posts: 96
Location: Zagreb, Croatia
Hi Karol,
the stuff I did to your data is done in GPRSoft so I guess its a suggestion to try that software for further postprocessing.
Getting much clearer than you got is probably impossible if you think about it:
-there are two metalic stripes (rails) near the survey line
-there are additional metalic and electric noise influences (rail pins, electrical conduits, signal conduits....)
- the beams are in the worst posible place (on surface, perpendicular to direction of the survey)
-the material of the balast is chunks of rocks so you get a lot of scattering
- any kind of vehicle you ride the antenna on will add its influence (unless you make some kind of wooden sleigh and pull manually :D)
1. The general idea/difference between airborne and groundcoupled antenna is the way they are "tweaked"/calibrated for usage. Airborne antennas give better results if used "airborne"= lifted from the ground and "groundcoupled"=in contact with the ground. From actual surveys and Reinaldo's elaborate explanations the amount of lifted/contact is in fact connected to the wavelength of the antenna and the value should be 1/10 of wavelength (the maximum should be near that number). So if you lift the antenna above 1/10 and it is groundcoupled it will give you more noise, the amount of signal that penetrates into the ground will be significantly reduced (some of the signal slides out of the antenna footprint and never returns to the antenna) and you end up with lowsy data. Same thing works for the airborne antennas - if you keep them near the ground the amount of noise raises and you get less usable data. As for your comment about the difference of dielectric in air and ground, the specific value is calculated in air (you are raising and lowering your antenna in air) so you calculate everything with the air dielectric/velocity. You can try this for yourself by recording something simple and start with 0cm and lift to 20cm - after the 7,5cm treshold for 400MHz (1/10 wavelength) you'll be able to see the difference.

2. As I said I'm not aquinted with IDS equipment, so I guess they are recording the raw data in order to get clean data that can be processed by anyone and not to get it influenced by gain while surveying.

3. Argh, I'll have to work on my english more. You understood me exactly the opposit. OK. Avoid perpendicular to the direction of survey or paralel to the direction of survey because those are the angles that are best for recording the beams and you don't need to record them at all. Try with 45 degrees angle of the antenna.
changed the download file


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Last edited by bekic on Tue Apr 06, 2010 8:28 am, edited 1 time in total.

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PostPosted: Sat Apr 03, 2010 7:40 am 
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Joined: Fri Apr 17, 2009 7:52 am
Posts: 379
Location: Boden, Sweden
Hi Karol,
I think you are getting good help here from Goran. To what Goran has said I'd only add that you could increase the amount of traces/unit to be able to
discriminate the layers better.
When using GPRSoft PRO for layer determination one has to be careful to which method to use to define the layers. The automatic or
phase follower works best for continuous, slowly changing layers. I personally use the point method more often than not.
If you have any questions regarding GPRSoft PRO please do not hesitate to ask. I unfortunately cannot comment on Gred3D, but I'm
sure you should be able to get help from IDS.
Let us know if there's something else we can do to help.
Best regards and Happy Eastern!

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Geoscanners AB
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http://www.geoscanners.com


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PostPosted: Sat Apr 03, 2010 7:42 am 
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Joined: Fri Apr 17, 2009 7:52 am
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Location: Boden, Sweden
Hi Goran,
I cannot open your archive, Winrar says it is corrupted. Can you upload it again?
Regards,

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Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com


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PostPosted: Wed Apr 07, 2010 7:47 pm 
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Joined: Fri Apr 17, 2009 7:52 am
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Location: Boden, Sweden
Hi Karol,
I got a few minutes Today and decided to make a little video showing the processing of your data.
You can see it here:
http://www.geoscanners.com/videos/ids_p ... essing.htm
Let me know if you have any questions.
Regards,

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Geoscanners AB
Sweden
http://www.geoscanners.com


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PostPosted: Wed Apr 28, 2010 6:13 am 
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Joined: Wed Feb 17, 2010 4:56 am
Posts: 18
Location: Jakarta, Indonesia
GeoAdmin wrote:
Hi Karol,
I got a few minutes Today and decided to make a little video showing the processing of your data.
You can see it here:
http://www.geoscanners.com/videos/ids_p ... essing.htm
Let me know if you have any questions.
Regards,


Thx to u Reinaldo. That video increase my knowledge, especially for processing the GPR data. But I want to know, how to predict the permitivity in some hyperbol (using GPRSoft), If the value in the vertical line (Y axis) is depth value (in mm) and not in time value (in ns)?

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PostPosted: Wed Apr 28, 2010 9:21 am 
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Joined: Fri Apr 17, 2009 7:52 am
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Location: Boden, Sweden
You are welcome Hendraparley!
Please watch this video:
http://www.geoscanners.com/videos/hypfi ... itting.htm
It has been done with a somewhat old version now, but the principle stays the same.
Best regards,

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Geoscanners AB
Sweden
http://www.geoscanners.com


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PostPosted: Fri May 14, 2010 3:19 am 
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Posts: 18
Location: Jakarta, Indonesia
@ Reinaldo : Thx again Reinaldo. But I want to ask you the another one (pleasae don't be bored to answer my question :D )

Oke, to the point

Sometimes I feel so difficult to determine the top or bottom of an anomaly in radargram. In radargram that I attached in here, shows that there are an inverse hyperbolic shaped (the anomaly), where I know that anomaly is fibre optic cable (the information I got from local people who saw the installation). Oke, I will focus in first anomaly,which can we see at a distance of one meter from the initial measurement and the anomaly appears in range depth from 0.35 meter until 0.90 meter. From that first anomaly, we can see that there are 4 inverse hyperbolic. What I ask in here is which one the top and which one the bottom of the anomaly (fibre optic cable) ?

PS : Sorry for my bad english language


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PostPosted: Fri May 14, 2010 9:47 am 
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Location: Boden, Sweden
Hi hendraparley,
Your English is fine, we are not native English speakers neither. As long as we understand each other then everything is just fine.
To your question:
The depth to the top of the first hyperbola is the depth to the top of the buried object, the rest are multiple reflections that will not
tell you the diameter of the buried pipe in this case, or the bottom of it as you suggested.
There are several formulas to estimate the diameter of buried pipes, rebars etc.
In GPRSoft PRO and many other software packages as well there are tools to estimate the pipe diameter based on an accurate knowledge
of the dielectric constant of the media the object is buried in.
Let us know if you have any more questions.
My best regards,

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Geoscanners AB
Sweden
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PostPosted: Mon May 17, 2010 3:26 am 
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Joined: Wed Feb 17, 2010 4:56 am
Posts: 18
Location: Jakarta, Indonesia
As u know Reinaldo, in here I use GPR Mala Easy Locator, which the Y axis is show depth and not time. And after I convert the raw data (.jpeg) using Matlab, the unit from the raw data there is meter for the depth and for the distance (X axis) and I must change into milimeter (for depth) and still meter (for distance) - you can see it from the data that attached in here (4545.sgy). The problem is, I have been use GPRSoft and I always difficult because the Y axis in GPRSoft is in time and not depth, beside that I have been try to, how to fitting hyperbola in GPRSoft or ReflexW, but I think the diameter is input manually by us not automatically.

So, in here, if you not objection, can you show me in video form, how to estimate the diameter the fibre optic cable (the first anomaly that I show you in previous post), if the constanta dielectric unknown and the Y axis is in depth. In here I will attached the data (4545.sgy).

Before and After, I just can say thank you.

Best regards

Taufik


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