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  #1  
Old 12-15-2017, 09:36 PM
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Default Can you get more depth in the ground than in an airtest?

Just curious about this. I've heard people say their detector will only airtest x inches, but goes deeper in the ground. Then I read that a proper airtest is the max you can expect out of your detector. I know ground conditions are the determining factors for an object in the ground and EMI can really make an airtest go wonky. Is there a definite answer?

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Old 12-15-2017, 11:05 PM
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Yes, no and maybe???
But there probably isn't a way to prove either argument.

I know I've dug a couple coins with my old compadre that were definitely deeper than it will air test, but there are too many variables to say why how or when it happens. Ground conditions, ground balance, co-located targets, EMI and the list goes on.

I like to chock it up to good fortune when it happens, give thanks,
and keep on swinging.

If we could just get Steven Hawking to take a break from string theory and start designing detectors we could probably get some answers.

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Old 12-16-2017, 01:22 AM
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Yes, but the coin needs to have been sitting in the ground for quite some time (very broad time range, I know! ). There's this thing called a "halo effect" which is the result of ions from the metal seeping into the ground, therefore making the target appear larger than it actually is. When the target appears larger, the detection depth increases (duh!).

Do a google search on the halo effect, there are some good sites out there.

http://www.njminerals.org/metaldetec...aloeffect.html

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Old 12-16-2017, 03:04 AM
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Depends on the soil and how long the coin has been in the ground. Certain types of tough ground can hinder depth for a lot of detectors and an air test may get better results , but in other places or soil types/conditions , as long as the target has been there a long time its possible to get better depth than an air test. There are a lot of variables but it happens.

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Old 12-16-2017, 03:17 AM
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Never heard this...
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Old 12-16-2017, 08:20 AM
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Originally Posted by TabZilla View post
Yes, no and maybe???
But there probably isn't a way to prove either argument.

I know I've dug a couple coins with my old compadre that were definitely deeper than it will air test, but there are too many variables to say why how or when it happens. Ground conditions, ground balance, co-located targets, EMI and the list goes on.

I like to chock it up to good fortune when it happens, give thanks,
and keep on swinging.

If we could just get Steven Hawking to take a break from string theory and start designing detectors we could probably get some answers.
Originally Posted by X-Terra70 View post
Yes, but the coin needs to have been sitting in the ground for quite some time (very broad time range, I know! ). There's this thing called a "halo effect" which is the result of ions from the metal seeping into the ground, therefore making the target appear larger than it actually is. When the target appears larger, the detection depth increases (duh!).

Do a google search on the halo effect, there are some good sites out there.

http://www.njminerals.org/metaldetec...aloeffect.html
Originally Posted by ohiochris View post
Depends on the soil and how long the coin has been in the ground. Certain types of tough ground can hinder depth for a lot of detectors and an air test may get better results , but in other places or soil types/conditions , as long as the target has been there a long time its possible to get better depth than an air test. There are a lot of variables but it happens.
Originally Posted by snickers104 View post
Never heard this...
Thanks for the replies guys. Xterra: thanks for the link to that article. I just did a quick skim reading of it and it's very interesting. I bookmarked it so I can read it in depth later.

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  #7  
Old 12-16-2017, 04:56 PM
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Originally Posted by X-Terra70 View post
Do a google search on the halo effect, there are some good sites out there.

http://www.njminerals.org/metaldetec...aloeffect.html
Awesome link, X-T! Bookmarked that one - fantastic overview of halo effect and itís wide impact on detecting, from test gardens to detecting after it rains.

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  #8  
Old 01-06-2018, 02:01 AM
George (MN) George (MN) is offline
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Originally Posted by NCtoad View post
Just curious about this. I've heard people say their detector will only airtest x inches, but goes deeper in the ground. Then I read that a proper airtest is the max you can expect out of your detector. I know ground conditions are the determining factors for an object in the ground and EMI can really make an airtest go wonky. Is there a definite answer?
Outside, people would only consider a valid test one with no EMI. But indoors, people are divided as to air tests being the highest setting that provides a beep, or is it the highest setting that gets a beep without any extra noises?

The in house noises are not likely heard at the nearest park or school.

Almost any detector will air test 10" on a dime if average or above. Some cheaper units will air test 8"-9" on a dime. Anything that does 11"+ amazing.
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  #9  
Old 01-08-2018, 10:10 AM
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Air tests are of value, many of the high audio gain units will air test silly deep, mine gets a silver dime at about 14" with a sniper coil, but in my soil it would be around 50% in ground with said coil.
Mild soil is where the high gain units shine on depth.

Originally Posted by George (MN) View post
Outside, people would only consider a valid test one with no EMI. But indoors, people are divided as to air tests being the highest setting that provides a beep, or is it the highest setting that gets a beep without any extra noises?

The in house noises are not likely heard at the nearest park or school.

Almost any detector will air test 10" on a dime if average or above. Some cheaper units will air test 8"-9" on a dime. Anything that does 11"+ amazing.
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