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Masking and Iron Discrimination

SixBits

New member
I'm trying to learn as much as I can about my AT PRO.

In the iron discrimination section, the Manual discusses masking of a coin by an adjacent iron nail. It suggests that the user unmask the coin by adjusting the iron discrimination to just barely reject the nail. The result is that the AT PRO measures the combined conductivity of the nail and coin and registers and sounds a combined VDI higher than the discrimination setting, thus revealing the presence of the coin. That makes sense if you know that there is a nail masking a coin under your coil and you know the VDI of the nail alone, but you don't. This seems like a catch-22. What am I missing?
 
I agree, you don't know if anything is being masked.

My interpretation of that masking tip (also described in the instructional videos) is that the technique described applies when you are hunting in and area that you feel is heavily trashed with a particular class of nuisance iron objects (such as an old homestead that may be loaded with old cut nails).

How do you know about these iron objects ? Good question, my "guess" it's most likely because you already dug a bunch of them and would like to not see them but at the same time, the best way to eliminated them is to use as minimal iron disc as necessary. The theory from the air test they show in the video suggests (to me) that using minimal iron discrimination can also help in finding good targets. Theory being, is that a good target (by itself) may be to small or to deep to detect but when combined with a nearby piece of iron or one that is actually masking, when they add, the combined conductivity may be good enough to now the other target.

It sounds plausible to me but could be more of a marketing tip.
 
Frank G's theory of having dug a couple of iron nails and just barely disc them out is how I understand it as well. In such situations or other types of heavy trash, I personally never use any disc, ever and listen for the mid and high tone tic's, chirps and whimpers peeking through the iron and low tone grunts. In those types of situations its tone pretty much solely on to dig or not......not t i d. HH jim tn
 
SixBits said:
I'm trying to learn as much as I can about my AT PRO.

In the iron discrimination section, the Manual discusses masking of a coin by an adjacent iron nail. It suggests that the user unmask the coin by adjusting the iron discrimination to just barely reject the nail. The result is that the AT PRO measures the combined conductivity of the nail and coin and registers and sounds a combined VDI higher than the discrimination setting, thus revealing the presence of the coin. That makes sense if you know that there is a nail masking a coin under your coil and you know the VDI of the nail alone, but you don't. This seems like a catch-22. What am I missing?


The method mentioned still may not actually identify the coin unless you get the occasional high tone or "pip" while swinging the coil over it ( which does happen sometimes ) , many times its just a high enough tone and/or VDI to let you know there may be something better than a nail there. But.....if you know how the detector reads "any" nail , and set the discrimination accordingly then atleast you know you are not only weeding out a percentage of the nails but there is a chance of seeing a little better through the iron mask. You do have to be willing to dig or investigate all targets above the discrimination level though.
 
OhioChris is wise. This is a conundrum every VLF faces. My advice: get some nails, get some good targets and make a test garden. Try all sorts of permutations of nails in with good targets. Develop a connection with your detector, learn to speak with it. Observe the signal from every angle. Try slow and fast sweeps. Develop that good feeling for how a masked coin responds. You can talk all day on the forum, it will only do so much good.

FYI: if you're hunting areas that you know have good stuff but are not getting anything, and suspect masking is the problem, consider a PI with an adjustable ground balance. The ground balance on a PI is an entirely different form of discrimination and can eliminate iron masking entirely in a lot of cases, especially if you are hunting high conductors like silver. Here is a video that demonstrates this principle: https://www.youtube.com/watch?v=38qI7Xz2BBo
 
jim tn said:
Frank G's theory of having dug a couple of iron nails and just barely disc them out is how I understand it as well. In such situations or other types of heavy trash, I personally never use any disc, ever and listen for the mid and high tone tic's, chirps and whimpers peeking through the iron and low tone grunts. In those types of situations its tone pretty much solely on to dig or not......not t i d. HH jim tn
I agree with you jim tn I use to disc to 27 or even 40...and I notice sometimes you get broken noise so now I hunt with no disc at all just listen to the tone. PRO ZERO NO DISC
 
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