Some standardized Metal Detector performance test suggestions

I'd like to see some of your ideas for testing metal detectors. My intention ideally is to film the tests. Please add your ideas, suggestions, etc. below. Post pics/videos if you wish. Giving measurements would be helpful eventually.

When the time comes - For any in ground test results it would be nice to know your GB and mineralization levels if possible.

Here is what I have come up with so far outside of a typical coin garden test (of course different settings and coils should be tried):

1. Monty’s Nail Board Performance Test
2. “Modified Monty” – A coin below/above the nail board by 1”, 2”, 3”, etc.
3. Row of coins – see the recovery. Different coins (sizes and conductors) and different spacings. e.g. O O O O or O O O O or O O O O etc.
4. #3 above but with nails between – horizontally, vertically, various angles. e.g. O I O I O or O - O - O or O / O / O etc. (edit - per JJ, use bottle caps in between coins as well).
5. Different size nail above coin at various measurements (1”, 2”, 3”, etc.). Maybe with different amounts of coins and nails...
6. Coins with nails between/around, etc. at a variety of angles
7. MarkG's - Coin and Nail Salt Solution test - see below
8. Tom's 90 Degree Nail and Dime test - ( O ---- )
9. Tom's 3D Test - See below

Thanks,
Albert

Revision 3 - last updated May 18 2012



Edited 3 time(s). Last edit at 05/18/2012 09:51AM by earthmansurfer.

Unfortunately a nail buried for 50-100 years differs quite a bit from a fairly new one on top of the ground or recently buried..

Indeed it will give you an idea(ball park) especially if hunting in newer areas and Monte has some good ideas but certainly skeptical at best relative the info gotten from such tests..other than basic speed of the detector in hand.

Hi,, I guess it depends on the site you are hunting is where you should and could focus your tests and your test objects....Personally I'm totally surprised if not shocked that nobody even focuses their thoughts or tests based on the site that they normally hunt ....In my case I hunt older parks etc. where the main culprit is the dreaded old rusty beer bottle cap....These things are still very prevalent in the places I normally hunt and do a nice job if not a perfect job of masking the older gems that I seek and desire....So perhaps you could add them to some of your test scenarios ....HIH....JJ

So who has a 50 - 100 year old coin garden? Who is going to go find coins in the field and bring multiple detectors with them? (It is a lot of work, I know this).

I see what you are saying but we have to work with what we have. Just like air tests aren't ground tests, but they still point us in a direction. Do a recovery speed test out of the ground and it still helps to understand a machine.

On the other hand, my E-Trac doesn't do good with recovery speed tests but it outperformed my V3i and Omega in the field (in mod+ iron).

So, what is your suggestion Dan?

JJ - This thread is for you to add your suggestions. Lay it out ;-) (Edit - Good idea JJ).



Edited 2 time(s). Last edit at 05/16/2012 04:34PM by earthmansurfer.

Hi,,,Hey Albert you could just substitute bottle caps in place of your nails....That would be sufficient
enough to cover a lot of different hunting scenarios .....HIH....JJ

Tom suggested adding strong salt water to your test garden targets before covering up with dirt.
This allows them to corrode or leech out to the surrounding ground faster.

I'd like to see this:
Take a dime size coin and bury flat at 6" deep.
Before covering up coin pour one cup very salty water on the dime size target, then add 3" of dirt.
Next bury a 2" rusty nail flat directly above the coin, pour one cup very salty water over the dime size target and finish filling in the hole.
Let it set until you get your CTX.
Let me know what you find. Oh, by the way try the Etrac on this setup too.


Thanks in advance.
Mark.

Personally I am with fellows who say test in the field....good info on the salt water as I didn't know that...heck I know the Explorer series are painfully slow so you need a faster unit...I moved slowly when I was 20 and now close to my mid seventies my wife says if I move any slower will be going backwards and so Explorers and I get along just fine just as an old hunting buddy killed them with a Whites XLT as he was a fast mover....Heres something you might try get a signal that you just know is a goodie and try different settings on your unit to see what works best in your mineralization and hunting area as might surprise you what different settings will do rel depth, audio etc...
Honestly respect Monte and his tests just shooting from the hip and not being sarcastic as in the field is where it counts... but indeed some of these tests can be eye openers.

Albert, 2" rusty nail over a U.S. quarter.....like the test @ FMall. I have pulled dimes with rusty nails above them in the hole...in dirt...not air. Thanks

Tom, I'm adding your post here as it is quite apt:

Since this forum/web-site is becoming more international............ I am trying to devise a 'standardized' method for 3-Dimentional testing.

Nail on top is obvious. What TYPE of nail. What SIZE of nail.
Depth/distance should be a standardized distance. Probably 1-inch........... or maybe 25mm.
The coin needs to be fairly small........ dime-sized. A quarter is 2-1/2 times the mass/size of a dime..... and is too big. We hardly find quarters. We find more dimes and small coins the most. Keep it realistic.

I have a 'standardized' 90-Deg bent rusty square-nail glued to a 1" thick piece of 4 x 4. I have a clad dime glued on the other side of the wood. As of yet............. no detector in the world has passed this test..... failing to detect the dime.

If separation is increased from 1" (between the nail and the dime)........ the test becomes excessive absolute.
If the size of the nail (that I have choosen)..... is increased.................. the test becomes excessive absolute.

With this wooden block placed on (sanitized) dirt .... with the nail on top............ another large 'variable' is......... sweeping this complex target scenario at different coil heights........ ultimately altering resultant.

My thoughts are............................. If a metal detector Mfr can ID a dime (not correctly..... but as a non-ferrous target)............ that is 1" below a nail............ this would be a superior starting-point. To find a dime several inches below a nail .................. is asking too much (right now). ((( Unless a paradigm shift is employed ))). "Front" coupled with angular or "side" scan can perform such............. as seen/witnessed in airports. But a inductive loop (coil) on our metal detectors is "Front" 1-Dimentional ONLY.......... technology. Tom Dankowski

Albert........ thanks. . . . . as I too.... feel like many folks missed it.

I think the only way to get reliable results is to have some standard by which to test. Real world has too many variables to deal with.

I like the go no go tests. Can it detect the coin yes or no. Tom's 90 degree nail and dime sounds like a great go no go test. Sounds like right now every detector made is a no. Maybe the CTX3030 will be a game changer and get a yes.

Keep it simple and the the result a yes or no. Interpretation allows too much variability. A clear standard with clear yes or no results.

One other thing that makes this very hard is detector settings. I think that to be fair detectors should be tuned to the point of just being stable but not to stable. If you can run it wide open then do so. Then run it at 50% of max. Now you have full and half power readings. Discrimination wide open, past that it starts to get crazy.

Good luck with your testing I am sure a lot of us will be watching.

I like Bryanna's idea of varying sensitivity...as we all know mineralization/sensitivity levels vary worldwide. And Mark G's salt solution.

The problem with 'full sensitivity and 50%' is that every machine is differently calibrated/scaled, 50% can be way different from machine A to machine B. Not to mention that 50% is just a mark on a dial. If it was 50% sensitivity, it would represent a modest 10 - 15% depth loss, if it truly gave half-depth, you would actually be looking at about 1/60th the signal.

If sensitivity is that individualized in callibration, to each machine...then what is the point of testing at 100% sensitivity, or testing at all ?

Thanks a lot for the comments guys. I updated the initial post as best I could.

Consider this a work in progress. Eventually we can put the above list (with notes/addendums e.g. - sensitivity comments) in some order of importance.

Feel free to suggest anything that you feel might improve the above tests. The only thing I can think of is perhaps to have just a few (not too many) standard tests, to get us going, then some more additional tests or "level 2" to take a deeper look.

Anyway, My Rutus Jupiter just arrived off Ebay, so I'll try to apply some of the above tests in the next week or so and start a separate thread just on this machine using a bit of the above "guidelines" in testing.

Thx,
Albert

Quote:"what is the point of testing at 100% sensitivity?"
You're absolutely right, in a way. 100% is the maximum the machine will do, so ought to be representative of its best capabilities, but of course there are machines out there that have a 100% that is completely unuseable, and turning them down to '6 out of 10' sensitivity is the most you can use in real-world detecting.

STANDARDIZATION is 'key'
STABILITY is 'key'
VARIABLES removal is 'key'
Maximum STABLE performance is 'key'

There are going to be 'variables to the variables'........... we just have to do the best we can. MY SPECIFIC testing tools (test standards) are always 'standard' to ME only. It is impossible for someone else to have the exact same standardized test-tool that I have. Your nail may be bent 1-Degree more..... it may weigh 1-gram more, it may be oxidized 17% less........... may be oriented slightly different on your 1" thick wooden block ....... etc....................

I have painstakingly crafted/constructed/selected/verified/tested/configured my complex 'test-target combo' test-standard.... for the masked dime to be "just barely" masked. Just barely undetectable. This way............ when a new detector is released........... the slightest technological improvement in this department... can then be easily recognized/identified/witnessed/verified and ................ most importantly......... measured. (((Then...documented))).

Removing variables is not easy!
Scientific approach is mandatory.

This/these type(s) of testing is what really determines the 'performers' ........... thus improving our odds, increasing the success-factor...... and saving our (already limited) time.

If I had the time....... I could write a book on the amount of accrued education this 1" thick wooden block has given. Different coil sizes,,,, different coil configurations,,,, different transmit frequencies,,,, coil sweep speeds,,,, distance from coil,,,, different Ground Balance settings,,,, different Disc settings,,,, microprocessor clock-speeds ............... etc....................

Very interesting discussion, makes me wonder how efficient is any given detector, maxed out or not, stable or erratic? In other words how much of the power is going into the detectors detecting ability?How efficient is the detectorist, as witnessed and wrote about by Wild Wally in the "Most Impressive Find" Tom's sounds like a penny feels like a dime? I know what a coin sounds like but am nowhere near that efficient, guess thats where a test garden would pay dividends!



Edited 1 time(s). Last edit at 05/18/2012 09:22PM by rapidroy7.