Masking

OK I have been hunting and air testing in an effort to learn and improve my trash to treasure ratio. I have been wanting to find a Rusty Nail buried deep in the ground to use later for some Masking Testing. Today was my lucky day since I found one - Yea! Just as a side the find was interesting. I was hunting a trash invested local park - after numerous flattened aluminum cans I decided I needed to change my strategy and start digging only deeper targets. Well after I while I found a high toned target reading about 10 inches. I went over it in both directions and the signal was consistent but was faint and I had to have the coil pretty tight to the ground to hold the signal. I took my Safari out of Auto and ran at about 19 and the signal stayed strong and clean. I though hmm this is looking pretty good from some Silver since my TID confirmed what my ears were hearing which was a 37 to 38 . So I started to dig and dig and dig. I was pretty much down about 10 inches when I found target a nice 4 inch long Nail. I ran the nail over the coil and nothing it just nulled out like Iron should. Then I rechecked the hole and nothing with either my Pro Pointer or the Safari. So I had to conclude that somehow this deep nail was able to create a return signal that matched a high conductor - maybe this was an example of Halo?

So now back to then intent of this Post - Masking.

When I got home I took out my 4 inch nail layed on out the ground along with some several coins in a row. The nail was perpendicular to the coins. So it looked something like this:

o o o o I o o o o

The distance was maybe inch or inch and half between each coin and the nail. So I would swing my coil along the coins: coin- coin - coin - coin - Nail - coin - coin - coin - coin The Safari had no problem seeing each coin and then nulling on the nail. No Masking occurred.

So in this situation my conclusion was if to swing the coil over coin or coins and nails laid out like above I would have not problem hearing my coins in the ground.

Next I changed things so when standing at the detector it looked like this (I turned 90 degrees):

o
o
o
o
___

o
o
o
o

So now things have changed. When I was swinging my 11" pro DD coil over the the coins if the Nail was anywhere under the center section of the coil - Nothing just Null So true to what I had heard and read the Nail was masking the coins So if a Nail is under any part of the center of a DD coil then anything else under the center section is masked.

So hear is my question. I had read and heard that if you go over a target in two different directions, and in one direction you get a good tone and ID and in the other you get nothing then it is probably Iron trash and you should move on. Well I agree but what I just learned is it could be a Coin or some other treasure near iron. With my deep rusty nail I got a high if not somewhat iffy signal in all directions. So to me it seems if I get a good solid tone in one direction but loose it when I turn 90 degrees I very well could have a coin or some other treasure underneath my coil. Am I getting this right or am I missing something. I should dig not walk away.

Thanks

Bryanna

We've been hunting trashy yards the last month and have been able to pick coins out of the trash with a slow swing speed using a DD coil that you could only get the coin signal by swinging in one direction and a very narrow window at that. I'd say it depends on the area you're in and the potential for good targets being in among the iron.

That is absolutely correct. Too many folks are reliant upon good 4-way hits.

When you DO have only a 2-way hit........... this is where audio response/presentation becomes important. Is the high-tone audio 'clean' sounding during the good 2-way.............. or ..................... is the preamble/postamble a bit washed-out. ONLY experience; subsequently, creating 'skillset' can start to generate higher percentage success ratios.

Bryanna, NASA-Tom hit the nail on the head with his statement. No pun intended. Memorize it...especially........'is the preamble/postamble a bit washed-out'. Lots of bad targets follow that audio behavor.

Unfortunately your doing your testing out of the ground with the halo of sorts broken...Different ballgame in the ground.

As far as digging cans heck a coin or ring just covers a small area while a can covers a big area and all will fall into place in time with some field experience..

One wonders how many good targets the average guy or gal has missed because of masking....and of course even the best most experienced detectorist gets fooled now and then.

In addition to sizing the target another good test for a can is to raise the coil off the ground, if you still get a good solid signal at 10-12 plus inches or more it is most likely trash or big iron. If I'm digging relics I might still dig the target.

Ok now I know that a nail under the sweet spot of my coil will mask a good target that is also under my coil at the same time. Now here is the million dollar question. I am using a Safari that uses minelabs FBS technology. Is there a detector out there that under the same situation will see the nail and the coin but still tell there is a coin. My guess is that an Etrac will do the same as my safari, also ad the explorer. So FBS fails this test. How about an F75 or a CZ3D. Maybe the new XP deus would tell me both items are under my coil or at least tell me a coin is there. Is there any Detector made that will not mask that coin.

P.S. I did try all metal motion with my Safari and all I heard was the low tone from the Iron and a Low TID number of -10 as well. No indication of a coin.

I have been thinking about upgrading to an Etrac but not sure I am going to gain a lot. My Safari has both Ferous and Conductive tones, has Quick Mask in the guise of All Metal Motion. Has the same FBS engine just less resolution in its discrimination. If I am willing to go low and slow will an Etrac find more stuff? This gets back to the million dollar question. What real advantages do different detectors really provide.

When not masked my Safari is Deep. No question. It is also sensitive to small targets. But if all the trash is masking what I want to find what good is depth and sensitivity?

Please do not take this as someone who is frustrated I am not, my purpose is to learn and understand better. So please feel free to enlighten this green horn! One reason I really like this forum is people do take the time to think about what is really happening and in those discussions a lot of insight into how our detectors work comes to light! A curious girl I am.

I would not recommend upgrading to the E-Trac .............. as it would be a more expensive unit that would end up with the same end-resultant. Any CZ will fail also.The F75SE with 5" DD coil ........ or the XP GMP (or the much more expensive DEUS) will handle this scenario better.

Bryanna ....

There is advancements being made in detector technology...

The XP detectors are the type machine I have wanted for year's...it such a simple request but one the manufacturer's stray from...

till the XP designer got it right....

We the detectorist need the ability to control the iron disc resolution to a cutting edge degree of accuracy...Your nail test proves this....the Safari does not have enough resolution to deal with the horizontal nail...it takes care of the vertical nails fine because it is set high enough to discriminate the horizontal nail.. make sense....

A horizontal nail if set too low will double beep on a detector yet the vertical nail will still be quite...What a fine resolution does is allow more of the nail to be accepted right to the edge of double beeping...on a discriminator that rejects from iron to zinc that's a small window....but take a machine that has opened up the iron range into a much wider window...Well you can now go from full horizontal nail reject to right at the edge of signaling...it's a tight area but able to be fine tuned with the proper machine...

set it to start double beeping on the horizontal nail then turn it up ever so slightly till it discriminates out and anything that is lying in close proximity will also signal like say a coin...now the coin in close proximity might not read on a meter like you want it to but it will signal...


Here's an example...say the horizontal nail rejects at 20 on a detector but on 19 it signal's perfectly.....you have a dime that reads 85 but when it close proximity to the horizontal nail it will not read above 20 so it's rejected...

but say that all that was required to silence the nail was 19.3 on the disc...well the dime will add enough up averaging to get it to 19.5 but not 20...but it does not need 20 does it...it just needs to be above the 19.3 to signal...

when you start tying to unmask in nail ridden area's ever little bit of iron resolution help's as you are now learning...

I commend you on doing the test....You wont believe how many people will detect their whole lives and never bother to learn or try to learn what you have begun to notice..

Here's a video I did of just such a test you are talking about....I am using the XP-GMP but I think you will see where fine tunability is the essence of unmasking....
[www.youtube.com]

Now that video was not to bash the T2 but was to show the advantage of fine tunability iron disc range...

it's easy to deal with big iron in a site just dig it up and remove it...it's the nails that are in untold abundance that are masking the real treasure's...And the hardest to deal with...

The test we do are just say north south east west swing's...But imagine to yourself what the nails underground look like...they are in every conceivable angle and mix on top of one another like a bowl of vegetable soup...A 1 dollar gold piece laying under one nail will be rejected in 2 inches of dirt...image 30-40 more nails in a cubic foot of dirt....imagine all the target's being lost ...

good work


Keith

.............. and we are always/constantly testing and measuring on only a 2-dimentional plane. X-Y axis only.

What NEEDS to be done is...... 3-dimentional X-Y-Z plane. Put that coin about 1/2" below a nail (this would be 'Z' axis) ....... and see what happens. What if the coin were several inches below the nail.......... yet.......... still within detectable range.

Will some company take us to the next level as Tom said we need X-Y-Z does the deus do that or can that be an software upgrade?? I think Fisher and Tek need to pull down their pants and bring us all to the next level for the next few years and let us update our software over the internet...It would seem after what you have to pay for the deus Fisher/Tek could be a few hundred bucks lower but offer more???

LowBoy

TAKE A LITTLE TIME KICKBACK AND WATCH SOME OF MY DETECTING VIDEO'S BELOW ON YouTube

[www.youtube.com]

If you don’t dig it, then how are you going to know what you’re missing!
How can you have your pudding if you don’t eat your meat!

What we need is a detector that we hang out the window of our car. As we drive down the road at 55 MPH Carrie Underwood comes over the speaker announcing that a gold coin is in the field 1/4 mile ahead.

I am not sure about Carrie Underwood, more like Sean Conery. I do get the point, if it was easy it would loose much of the wonder and excitement of treasure hunting. But that being said, it is the way of technology that manufactures will keep improving their products and the job of finding treasure will get incrementally easier.

It is my opinion, that the next major advance in detecting will come in the form of advanced signal processing. Discrimination is a crude form of signal processing. There are many aspects of the received signal that could be measured to build a database of responses from which software could preform additional analysis and give us more accurate information on the targets under our coils. Minelabs FBS gives us Conductivity and Ferrous content. What if we just added density how much would that help us to determine if the target is worthy of a dig.

Now Tom had mentioned that an F75 with a 5" coil would have better see through then the Minelab FBS this begs the question how much does coil design and coil size play in solving this masking issue. It is obvious to me that a smaller coil will cover a much smaller area and this alone reduces the chances of both a good target and junk target being under the coil at the same time. But what about other factors? Would the Etrac and F75 performance be much closer if the both had small footprint 5" coils?

Ok one more stupid question. Why is it that iron trumps silver or copper in the battle of which signals get sent back to the detector. If it was the other way around we would not be having this discussion because the high conductor would always shine through.

This is no perfect detector - The Holly Grail of detector technology is not in our near future and we probably do not want it any way. But some incrementally better technology and a lot more understanding of what goes on under our coil would be OK.

Bryanna

goodmore Wrote:
-------------------------------------------------------
> What we need is a detector that we hang out the
> window of our car. As we drive down the road at 55
> MPH Carrie Underwood comes over the speaker
> announcing that a gold coin is in the field 1/4
> mile ahead.

I think the point is user chooser which voice we want, Sean, Carrie or Peewee. Apps, tweeks or mods it would be nice to have more control. Of course we then would screw things up and want the mfg to fix it and waste whatever profits the sale netted while we gripe about it.
I think I needed a longer nap.
Tom

Past(or)Tom
Using a Legend, a Deus 2, an Equinox 800, a Tarsacci MDT 8000, & a few others...
with my beloved, fading Corgi, Sadie

One other thing Bryanna...Slow the sweep speed way down on the Safari on the scenario that is keeping you from hearing the coin's...get real slow..

If you try to run the safari in an iron area with a sweep speed of a regular detector it will mask just about everything out.....

see if a ultra slow sweep speed does not work ont he failed test..


You may already know this but if not give it a try...

whatever sweep speed you used for the passed test slow it down less than half for the failed test...the FBS machine work great at snails pace as far as holding depth .



Keith

You can set the disc to just barely reject your test nail on the E-Trac and get much better results as Keith mentioned.I assume you can do the same with your Safari.Just start with an open screen and use the small curser setting to eliminate only nail/nails and you will be amazed how well the fbs machines are able to unmask good targets in iron.They will hit a tiny US $1 gold coin between two rusty nails placed less than 3" apart .
Many folks run way to much discrimination in heavy nails and speed kills your recovery of good targets even with a super fast machine like the Deus.

This is all very good insight. But now reading this I might be confused with the nail masking issue.Bryannagirl originally got a good hit at 10 inches in the ground at least 2 ways but not sure if she got it in all 4 directions.Now did this target; the 4 inch nail really do any masking in the ground? We know it creates a mask effect once out of the ground. It nulls.There is no more in ground aurora once out of the ground to bring up the signal.So can we say that in some instances like round iron,moderately large iron that will give you a good north-south signal in the ground is really creating a mask?If the detector never nulled then I dont think so.It tricked us in thinking that we have a high conductor there.Now if there was a 50 cent piece underneath the 4 inch nail would that average down a little bit or stay at the correct id # for that perticular detector?If the detector already said the id was 38 or 37 I would think it would average higher.So the way I see it unless I could be missing something is all in ground iron junk is not all that bad. I think it is the iron that makes the detector blank out that we need to slow way down and listen to all 3 parts of the signal; the ramp up of signal, the body and ramp down of signal.Thanks, Steve

Yes.......... electromagnetic coil 'footprint' is very important. But....... microprocessor clockspeed is also important.
Also......... the microprocessor on the Minelab's are quite slow....... yet, MUCH faster on the new Fishers.
BUT......... the new Fishers are hyper-sensitive to iron.......... and the Minelab's are less sensitive (somewhat detuned) to iron.

Is one unit a trump-card over the other unit?
Is the 'somewhat detuned to iron' Minelab equiv to the faster microprocessor of the newer Fisher units? No......... not quite.

While I would not have been able to say this a year ago (before thinking really hard about this topic, and having "ideas planted" in my head by NASA-Tom and others), I will parrot what NASA-Tom has said in the past, because thinking through it, he is SPOT ON...the next MAJOR advancement with respect to "unmasking" will have to come through what he calls a "PARADIGM SHIFT." Shifting away from electromagnetic detection, and into some other technology. While small improvements continue to be made (small coils, fast processors, iron-fine-tuning ability, etc.), trying to find small metal targets amongst ferro-magnetic trash, within ferro-magnetic soil...that seems to me alot like trying to sense a burning match that you have just tossed into a raging campfire, using an infrared sensor. Kind of silly, when you think about it...no WONDER NASA-Tom states that roughly 90% of in-ground targets remain UNDETECTABLE...

Steve

Ray-Mo., you must have some of the mildest soil in the country, coupled with the shallowest $1 gold, and a sweep speed that allows a spider to build a web under your arm while you hunt. There's no way my Etrac will find a buried $1 gold piece in between two nails separated by only 3" using a normal sweep speed. The processor is just too damm slow.

Adjusting the iron disc will certainly help but how can you precisely know when you've got the disc just right? You can't know for certain. Disc too little and you find iron, disc too much and you miss deep high conductors. Too much sens and you false on the nail tips; too little sens and you've got no more depth than an Ace. You can approximate given what you're seeing, but in a 3D iron salad you'll miss stuff that a unit having a faster processor coupled with a tighter DD field will find.

I have a Type 1 $1 gold buried 6" in my red clay. My etrac with its factory Pro-coil has never been able to find it under any conditions and it there is no co-located iron. The only setup that consistently finds this coin is my F75LTD with the 15" coil. I have never been "amazed" by what my Etrac did in an iron infested site, in conductive or TTF.

You seem to have one hot Etrac finding stuff under manhole covers given what you've posted over there. And now Minelab is coming out with a hot new unit! Here's a tip: see your doctor for any erection lasting more than four hours...

------------------------------------------------
"Facts can be stubborn things..."

Ok, processor trumps this and iron rejection trumps that. I think we should refocus on what is really important in this discussion - understanding how our personal detector(s) respond to iron masking and how we can use that knowledge to get better at finding treasure among trash.

Bryanna

Bryannagirl, do you have the space to create a test bed? They are an invaluable learning tool and described in some depth within Tom's videos and on this site.

Heck, I literally have gold buried in my backyard!

Did you slow your sweep speed down and try your test again??? Or where you already doing this??

Need to know particulars if you are having trouble...

If you like the Safari thats all that matter's but to get the most out of it any info you have on how you are running it or setting it up will allow other's to chime in more...

Nothing wrong with FBS machines they just behave differently than VLFs...And the users to get the most out fo them will have to adapt..

All modern detector's are very capable...

But when you are really trying to get target's out of hunted to death iron it will take a certian machine and alot of trial and error and patience and lot's of sweat ..LOL!!

Keith

Hi Brianna,I believe the problem most newcomers have is not taking the time to truly learn their machine....they jump around from this detector to that one. I had a sovereign(bbs), a precursor to your machine. Keith nailed it....ya gotta go SLOW. Learn the tones. Learn to recognize the sound of a deep silver coin ( if thats what your after) . It took a while for me to get the hang of the sovereign,but after awhile I became one with it . You will too,just keep at it and I bet youll be amazed at what you get.