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Ground penetrating radar?
Posted by: JJames1610
Date: September 21, 2017 07:35AM
If anyone has any information about these metal detectors, i would like to hear from you. I mostly want to hear from people who have hands on experience, or have been in the field with people using them. Would like to know what is considered the easiest for two people to use. What brands are there to choose from, who in the USA sells them? Anything i should watch out for and stay away from. Thanks

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Re: Ground penetrating radar?
Posted by: Mega
Date: September 21, 2017 09:24AM
Have been looking at a few from Europe,even the cheapest ones are pretty basic and also still very expensive,at the moment the maths just dont stack up in terms of cost to reward ratio,so going down the route and actually paid for a extra large frame coil for using on a Pulse machine that then should do what i want at the moment.GPR machines can be basically the skies the limit and only worth it if you are totally 100% certain the the finds will exceed the expense and time in mastering use one,which in my mind is out of the normal skill sets of a detectorists.

Next step will be testing the large 6ftx6ft frame mounting over the coming months,or the other option that i am also looking at is the 41'' Concentric coil for my Nexusb MP,once again the maths also have too stack up in my favour,the current Pulse setup should do exactly what i want at a very reasonable price as well.



Deus and Nexus MP main everyday detectors

Displays on a Detector are really the equivalent of relying on sub-titles,give me a Analogue machine anyday.

Site specific use machines.
TDI Pro 20'' Mono
Nexus SE dual 9'' coil
Fisher TW-5 twin box
Crossbow PI Coiltek 14x9 Mono
Mirage PI 5'' Mono
DFX 18'' Detech
T2 SEF15x12
IDX Pro 15'' Concentric
Arado120b
B1 and B3
Trident11 Extreme NEL Snake


Mainly hunt deep ploughed and pasture sites,trashy roman/saxon and celtic permissions.

Re: Ground penetrating radar?
Posted by: Tom_in_CA
Date: September 21, 2017 11:02AM
What type objects are you looking for ? Individual coins ? Then IMHO: GPR is useless for that. You're better off with a standard machine. The "shape-showing" ability of GPR is AT BEST pixel sizes of 1" across. Hence all the objects we find (nails, tabs, coins, rings, foil wads, etc...) are all ....... doh ... 1 pixel ! :rolleyes: Hence you have gained no useful information.

Or if it's large caches you're after, I don't think GPR will benefit you there either. You don't get some sort of magical TV screen like picture of jar or box or whatever. Instead, you just get a "messy blotch of pixels". And the depth would be no better than a typical 2-box machine (like a TM 808).

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Re: Ground penetrating radar?
Posted by: Mega
Date: September 21, 2017 11:10AM
@Tom_in_CA,totally agree with everything that you have mentioned,twin box i still reckon would be the best way forward,i use a Fisher TW-5 which will hit large targets in clrar ground deep.forget about small individual coins or artifacts,with a twin box the bigger the item the deeper it basically goes,but its more of a site specific use machine for going in for the kill on say a hoard or other large artifacts.



Deus and Nexus MP main everyday detectors

Displays on a Detector are really the equivalent of relying on sub-titles,give me a Analogue machine anyday.

Site specific use machines.
TDI Pro 20'' Mono
Nexus SE dual 9'' coil
Fisher TW-5 twin box
Crossbow PI Coiltek 14x9 Mono
Mirage PI 5'' Mono
DFX 18'' Detech
T2 SEF15x12
IDX Pro 15'' Concentric
Arado120b
B1 and B3
Trident11 Extreme NEL Snake


Mainly hunt deep ploughed and pasture sites,trashy roman/saxon and celtic permissions.

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Re: Ground penetrating radar?
Posted by: Wayfarer
Date: September 21, 2017 01:15PM
I work with GPR at our office to do archeological research, and Tom is completely right. If anything, he paints a rosy picture. Ours is good for about 3” pixels. Our machine is on e of the less expensive ones at about $14,000. It’s great for identifying old foundations, tracing large underground pipes, or finding old cemeteries, but is useless for what we treasure hunters do. Maybe someday, but that day is far off.



Current detectors: White's V3i, MXT, XL Pro
Past: White's XLT, 6000D Series 3, Coinmaster 2DB, Minelab CTX 3030, Fisher Gold Bug Pro
Location: Western Idaho

Re: Ground penetrating radar?
Posted by: JJames1610
Date: September 21, 2017 08:25PM
Not looking for individual coins, cache type hoard. I would expect it to be of a stagecoach strongbox type container. Never dug one up so couldn't say the size.

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Re: Ground penetrating radar?
Posted by: Wayfarer
Date: September 21, 2017 08:32PM
For a large strongbox type target, a GPR still wouldn’t be the best choice. Ours is very large and heavy and is mounted in what is like a big push lawnmower chassis. It’s very slow too with lots of computer analysis of the data. Id recommend a Whites TM 808 or similar for what you are looking to do. You can just walk along over any terrain and it will sound off immediately to any large deep metal object or cache.



Current detectors: White's V3i, MXT, XL Pro
Past: White's XLT, 6000D Series 3, Coinmaster 2DB, Minelab CTX 3030, Fisher Gold Bug Pro
Location: Western Idaho

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Re: Ground penetrating radar?
Posted by: Mega
Date: September 21, 2017 08:54PM
Quote
Wayfarer
For a large strongbox type target, a GPR still wouldn’t be the best choice. Ours is very large and heavy and is mounted in what is like a big push lawnmower chassis. It’s very slow too with lots of computer analysis of the data. Id recommend a Whites TM 808 or similar for what you are looking to do. You can just walk along over any terrain and it will sound off immediately to any large deep metal object or cache.

Yep,totally agree with you,i did own a 808 but for the last 5 years have been using the Fisher TW-5 which basically are the same type of setups,they dont get used very often,but its the right tool for the job in hand,if anything that is as big as a safe that has been mentioned then that will certainly nail the target that is if of course a safe is in the ground in the 1st place.

The earlier TM800 was possibly a better machine than the 808,but a twin box in a situation like that would be the right machine for the job.



Deus and Nexus MP main everyday detectors

Displays on a Detector are really the equivalent of relying on sub-titles,give me a Analogue machine anyday.

Site specific use machines.
TDI Pro 20'' Mono
Nexus SE dual 9'' coil
Fisher TW-5 twin box
Crossbow PI Coiltek 14x9 Mono
Mirage PI 5'' Mono
DFX 18'' Detech
T2 SEF15x12
IDX Pro 15'' Concentric
Arado120b
B1 and B3
Trident11 Extreme NEL Snake


Mainly hunt deep ploughed and pasture sites,trashy roman/saxon and celtic permissions.

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Re: Ground penetrating radar?
Posted by: Mega
Date: September 21, 2017 09:30PM
Out of interest what detector setup have you been using or had you previously been thinking about using for this type of hunt ?? and have you all ready detected the area that you surmise it could be located,as a strong box container should be relatively easy too locate i would have thought due to the size of the thing.



Deus and Nexus MP main everyday detectors

Displays on a Detector are really the equivalent of relying on sub-titles,give me a Analogue machine anyday.

Site specific use machines.
TDI Pro 20'' Mono
Nexus SE dual 9'' coil
Fisher TW-5 twin box
Crossbow PI Coiltek 14x9 Mono
Mirage PI 5'' Mono
DFX 18'' Detech
T2 SEF15x12
IDX Pro 15'' Concentric
Arado120b
B1 and B3
Trident11 Extreme NEL Snake


Mainly hunt deep ploughed and pasture sites,trashy roman/saxon and celtic permissions.

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GPR ain't cheap
Posted by: vlad
Date: September 21, 2017 10:05PM
and which antennae to use.....hi freq, or low? (high freq has better definition but less depth)
Interpreting the data is where you find the devil.........what's real, whats a reflection, or area once dug? :throw:
Tom is spot on about images. I agree with Mega on a 2-box---but would opt for a TM-808 ground cancel from Whites.
I'd look at a Deepstar PI with big loop--or some similar (think Deeptech makes one.)

Re: Ground penetrating radar?
Posted by: Tom_in_CA
Date: September 22, 2017 01:53AM
Quote
Wayfarer
I work with GPR at our office to do archeological research, and Tom is completely right. If anything, he paints a rosy picture. Ours is good for about 3” pixels. Our machine is on e of the less expensive ones at about $14,000. It’s great for identifying old foundations, tracing large underground pipes, or finding old cemeteries, but is useless for what we treasure hunters do. Maybe someday, but that day is far off.

Good post. Ever since catchy glitzy advertisements showed up, it's been hard to dispel the notions. The depictions of cool star trek type computer screen images propel the misconception . And it's taken on a life of its own. Typically coming from 3rd world countries , where legends of hoards run amok. And they are all, of necessity "6 meters deep" blah blah . And you're a "poor sap" unless you spend $10's of k's on sophisticated crap. (A TM 808 on ebay for $300 is ... of necessity, not going to work).

People there hear these campfire stories, see the glitzy color ad depictions, and think they are going to buy a machine that shows them a magical TV-quality image of a jar, a statue, a box with hinges, or whatever.

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Re: Ground penetrating radar?
Posted by: REVIER
Date: September 22, 2017 10:07AM
On one of the Hoover Boys vids they were at some historical site on a huge farm and in one out of the way area in some woods there was a headstone of a civil war soldier.
Supposedly his body was found in a creek close to that spot long after a battle and he was buried right there...but nobody knew for sure.
They brought in a GPR unit and scanned the grave and did find bones so that was pretty cool.

For the application you are asking about I agree with the others...a two box unit would just make much more sense.



"What if doing the Hokey Pokey really IS what it's all about?”
F70, F2, Compadre, Mojave, Judge2 - 2017....Clad, 13 silver targets including a freaking Barber quarter, a beautiful walker and two V nickels...
Plus other cool stuff.

Re: Ground penetrating radar?
Posted by: Tom_in_CA
Date: September 22, 2017 10:37AM
Sure. I'm not saying there's not certain applications. For example bottle diggers can discern outhouse pits, just by disturbed soil shafts. Or something like what you're talking about.

But for jars with metal, boxes of metal, etc... A person will get just as much information from the beep of a metal detector (telling him "metal is there"), than a magical image of a bunch of blotchy pixels (telling him "metal is there").

It's not going to show jar shape, or box shape, or tell you what the object is, blah blah blah

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Re: Ground penetrating radar?
Posted by: Mega
Date: September 22, 2017 11:50AM
I personally think it all boils down too the 'cost to reward ratio' and with a GPR unless its a complete lost 'Aztec gold hoard' that you are 100% of find or a possibly story of a 'lost safe' then the twin box or even a decent Pulse like the TDI Pro with a large coil will also do the same job but a fraction of the cost of a GPR.



Deus and Nexus MP main everyday detectors

Displays on a Detector are really the equivalent of relying on sub-titles,give me a Analogue machine anyday.

Site specific use machines.
TDI Pro 20'' Mono
Nexus SE dual 9'' coil
Fisher TW-5 twin box
Crossbow PI Coiltek 14x9 Mono
Mirage PI 5'' Mono
DFX 18'' Detech
T2 SEF15x12
IDX Pro 15'' Concentric
Arado120b
B1 and B3
Trident11 Extreme NEL Snake


Mainly hunt deep ploughed and pasture sites,trashy roman/saxon and celtic permissions.

Re: Ground penetrating radar?
Posted by: Tom_in_CA
Date: September 22, 2017 05:01PM
Quote
Mega
.... even a decent Pulse like the TDI Pro with a large coil will.....

The problem with using any coin machine (especially a sensitive squirrelly beast like a TDI) is that they will not only do great depth on cache sized objects, but they will "ring the bells of notre dame" on everything else as well. Anything that can pick up coin sized items is going to mean that you'll spend forever-&-a-day trying to differentiate between large and small. Oh sure, you might THINK you'll just set your mind to mentally reject all smaller stuff/beeps. Right ? But no, it never works out like that. You'll spend all your time digging a bunch "just to be sure". And will perpetually have doubts if the little beep your hearing might not just be a big item that happens to be quite deep. See ?

Contrast to a 2-box machine which simply doesn't even see anything smaller than a soda can. Presto: The perfect discriminator for individual coins, nails, tabs, foil, etc.....

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