Standards - How to measure?

[wam]

Can we make a list of techniques and performance measurements, so we will end up with something like ISO standards. It will make possible to observe changes and confirm it in scientific way in simple lab. conditions.
In my case one of my detectors manual says: 25c US with range no less than 18cm.My second detector manual says that depth is estimated for aluminum plate 60cmx60cmx1cm in dry ground.
I believe that it is possible to measure magnetic field coming from detector and measure its ability to detect changes and properties by numbers rather than comments.
I have seen measurements made by government laboratories for one metal
detector (so it could be declare as safe for use by public) and all results appeared in many numbers.
It would be nice if some one can propose an electronic meter to measure detectors properties (sort of “SWR” for metal detectors).
At least help me with some info about this aluminum plate “reference”.
Regards,

[Qiaozhi]

I have seen measurements made by government laboratories for one metal detector (so it could be declare as safe for use by public) and all results appeared in many numbers.

Can you post a link to this information?

[wam]

Document was on paper and had all electromagnetic emision spectrums and powers. This document was made to certify detector from oversees into local market. I am not in position to post it but i will try to post some electro-magnetic measurments used in such procedure.
Regards,

[wam]

It looks boring but this is how it is done in the lab.

[wam]

I may explain that permitted limit of this emission is “62” and measured strength of magnetic field in distance 10 m was 21.89. It is a result for metal detector supplied from 2 x 9V batteries and with power consumption less than 30 mAdc.
On some other page was note that “Max. Sens. 18cm (For aUS Quarter) = 19 cm “.

[wam]

In air Tests colection

Hi, this is a link with number of range tests for coins (in air).
http://wwwdark.w.interia.pl/testy.htm

[wam]

Miss Metal Detector

Miss Metal Detector.
It is unbelievable that in such technical (measurable) reality most evaluations
are created in categories of contest.
Yes, it is hard to measure beauty, filings or art yet the same approach is the most common in the Forumers perception of the best from the best from the best detector.
I would like to bring to Your attention that beauty of engineering have its foundation in mathematics – simple relation between more and less became the supreme judge in pointing direction for progress in development.
One of the most successful idea for metal detector base on two factors:
1. – propagating electromagnetic field.
2 . – detecting (measuring) changes in field properties.

• The metal detector must create electromagnetic field, the father it goes the deeper ability to search. Are you capable to tell me how strong and how far the electromagnetic field propagates from Your detector?

2. How heavy may be the device capable to propagate max. EM field for 4 hours.

Questions above will define Your limitations in the contest for “the best” MD.
The winner will be the one who can make largest number in cm.
How to measure? – what about FLUKE millimeter capable to measure TRUE RMS up to 50 kHz AC mV? If we agree for antenna dimensions it will be possible to confirm reading for specific way of measuring and we will detect the best propagating electronic technology.
If you found it inspiring …

[mts]

Hi, this is a link with number of range tests for coins (in air).
http://wwwdark.w.interia.pl/testy.htm

Wow! What a great web site. Are those numbers for real? Also, I can't read the language but it appears that those numbers are for US penny, nickel, dime, and quarter despite the fact that they use the dollar sign ($). I looked up my detector and the numbers were right on the money. Can anyone else vouch for the numbers on this site?

[mikebg]

Wow! What a great web site. Are those numbers for real? Also, I can't read the language but it appears that those numbers are for US penny, nickel, dime, and quarter despite the fact that they use the dollar sign ($). I looked up my detector and the numbers were right on the money. Can anyone else vouch for the numbers on this site?

MTS, this is an european method to avoid decimal point. For example 1K means 1kohm, but K1 means 0.1kohm or 100 ohm. In the Poland site, the sign 1$ means one dollar, but $1 means 0.1 dollar, ie 10 cents.
Mike BG

[wam]

MD Test example site

It could give some ideas how to make Test Report and what to take for consideration during test.
http://www.itep.ws/pdf/GICHD_MDCatal...AnnexSTEMD.pdf

This site has more tests docs available.
Please notice the conclusion on page 15,
" In-air data measured with a detector set up to the ground should not be used for a prediction of detection ability to target detection for in-soil depth. "
It looks that the some detectors had in-air depth 2 mm but in-soil the same target about 300 mm.
Many peaple dyspiut this reality - it may bring some confirmation from trusted publisher.

[wam]

standard for MD evaluation

Hi,
This is a document for a way to conduct metal detector test.
The description is a bit detailed but it makes possible to compare performance of MD.

http://www.itep.ws/pdf/CWA_metal_detectors.pdf

[homefire]

LOL! I think I'll just stick to the Stick in the Hole, And What It found kinda science here.

Don't plan on selling the gov any thing anyways.

[mikebg]

Eurocoins as target standard

Eurocoins as target standard
The euro coin series comprises eight different denominations: 1, 2, 5, 10, 20 and 50 cent, €1 and €2. The euro coins have a common side and a national side. The national side indicates the issuing country.
You can use any euro coin anywhere in the euro area. The following link shows the common side:
http://www.ecb.int/euro/coins/common/html/index.en.html
Eurocoins 1, 2 and 5 cent can be used for discrimination test because they are ferrous.
Eurocoins €1 and €2 are too complicated. The Bulgarian dealers prefer to use €1 coin for air test because it is large. However the 50 cent coin is large as €1 and even generates larger signal magnitude at extremely low frequencies.

In my opinion, the most suitable Euro coin for international standard is 10 cents. It is the smallest nonferrous coin in Europe and generates signal as a gold ring and fairly large nugget.

[wam]

From above pdf " ...The targets used shall be the chrome steel balls ...
The minimum set is:
4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm and 15 mm diameter. "

With spherical shape there is no problems with its geometry but I can not come with any common available metallic ball suitable for measurements.
I agree that coins are more practical.

[Tinkerer]

From above pdf " ...The targets used shall be the chrome steel balls ...
The minimum set is:
4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm and 15 mm diameter. "

With spherical shape there is no problems with its geometry but I can not come with any common available metallic ball suitable for measurements.
I agree that coins are more practical.

Coins are definitely more practical, but are not readily available around the globe. Coins of different dates, of the same nomination, are often made of different alloys.
Different alloys have a different frequency susceptibility or different TC's and therefore respond differently.

In your extract above, "chrome steel balls" are recommended. Chrome steel? stainless steel? There are many, many different alloys, some are very difficult to detect, others very easy. A very small difference of one metal or other in the alloy makes huge differences.
Take for example a steel alloy that contains 14% manganese. It is non magnetic.

Or look at gold alloys. 24 carats, 18 carats, 10 carats? In the 18 carat group alone, there are dozens of different alloys, pink gold, white gold and so on, each alloy responds differently.

And this is only talking about air tests. Each different soil matrix has again an impact on the end results.

So, yes, we should go back to your original idea and establish a methodology for testing.

Tinkerer