Ground penetrating radar system

Moose

Moose

New member
I recently was asked the following question by a fellow surveyor but was unable to help out very much as it's not really my bag, can anyone comment?

I?m trying to find out whether any talented caver (of the BCRA / CREG / Beet Heeb mould) has developed a home grown ground penetrating radar system? They?re about ?8-10K to buy and quite expensive to hire as well. It would be fun to build one from scratch and I now have many projects just waiting to be attacked with a GPR survey.

The spin-off surface survey applications for cave location work are obvious, as with the right antenna you can get depth penetration easily down to 5-10m and possibly much more. I know someone who probably has the ability to make the coils and circuitry, provided I could locate a design.
 
ChrisJC

ChrisJC

Well-known member
I would have thought that a microgravity survey would be better than GPR as caves are often out of range of GPR.

I also concluded a few years ago that a DIY microgravity rig was a tough proposition for a DIYer.

Chris.
 
Tony_B

Tony_B

Member
Has anyone any experience of using GPR for cave location?

At SWCC we have a (home-made) resistivity kit but it isn't particularly user-friendly and the results have been inconclusive. It produces some great images relating to known cave but no-one has yet found anything new as a result of resistivity scans.

I've been thinking that GPR might be a way forward but my (admittedly rather brief) Google investigations only seem to come up with commercial users.

Any pointers most welcome.
 
Ed W

Ed W

Member
Tony,

I have seen GPR used to locate a large shallow cave passage in Iceland.  The details are published in "Laki Underground 2000 - The Bournemouth/Dundee Universities Joint Expedition to Iceland" prepared by Chris Wood et al, published by Bournemouth University in May 2001.  ISBN: 1-85899-127-7.

It would be better to get hold of the report (it includes some pretty self explanatory pictures) than for me to try and describe what was happening as I am by no means a geophysicist.

Hope this is of use,

Ed
 
P

Peter Burgess

New member
Never mind finding caves - there is a nice castle waiting to be "discovered" directly above a known cave in the middle of Reigate - never been excavated and little prospect of that ever happening. Its a nice little project waiting for someone, and may help immensely in putting the cave into its proper archaeological context. The site being a SAM, non-invasive methods are the only realistic way of taking a look at what might be there.
 
Mark

Mark

Well-known member
We have used GPR many times at Dover Castle and other places, its a proper dark art, the only time they seem to find anything is if you tell them exactly what they are looking for.

We were looking for some lost tunnels and they found a "void", subsequent drilling found nothing.

Waste of time and money in my opinion for locating caves.
 
TheBitterEnd

TheBitterEnd

Well-known member
This paper may be of interest as it compares different Geophysical techniques.

As far as Radar is concerned, having had a look at developing microwave frequency gear in the past, I think there is a good reason why these things cost so much and are probably beyond your average electronics tinkerer
 
kdxn

kdxn

New member
DIY GPR difficult.

You need a good quality instrument to get data that can be interpreted and even then interpretation can be difficult. A relatively shallow technique, I have seen depths of four times the antenna separation in optimal ground conditions.

There are a number of forums, that discuss DIY GPR, for the Geophys and Treasure Hunting communities.
One such can be found here:
http://www.geotech1.com/forums/forumdisplay.php?f=11

A low cost hand held GPR can be found here for Euro2500:
http://www.pulsediscriminator.net/index.html

 
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