Re: What better a metaldector of a GPR?|
July 22, 2002 at 23:04:04
In Reply to: What better a metaldector of a GPR?
posted by Jed on July 22, 2002 at 13:22:24
You might put this over on the geophysics forum and get more answers.|
I have used GPR for over 20 yr and metal detectors for over 30 so have some reasonable knowledge. There are lots of GPR websites with theory, etc., and you might want to check them out on a search engine.
The primary advantage of the GPR is that it sees reflections from lots of subsurface items with contrasting electrical properties, not just metals. For instance, you can located buried walls, voids, tombs, disturbed ground, cultural and natural geologic features within the ground. You can also locate metal which usually presents a great reflector. One typical use of GPR is to locate subsurface utility lines and the like. GPR penetration is based on the attenuation of the EM waves and is greatly affected by things like salt water, conductive clays, and other materials.
Metal detectors, of course, detect metals, and sometimes other conductive things and their penetration is also affected by subsurface geologic conditions.
Each unit has its own set of capabilities. I have been in places where a $500 metal detector works better than a $25,000 GPR. For archaeological purposes for non-metallic detection, the GPR is the best. Also, if you have complex metal in the subsurface, like a treasure buried among a bed of nails and metallic trash, the GPR may have the best chance.
Just because something costs a lot does not mean it will do what you want it to, it will just do what it does. It depends on your problem.