Higher Sensitivity CAN mask targets as the detector sees too much!

[Doug[Manila]]

Read Mike & RickND's posts below...also went over to the EX forum and they have a lively discussion on sensitivity settings.

Have this fav site where I've been hunting with two of my buddies. We been over this place with Tesoro uMax, Fisher 1266x, Whites XL Pro and even Minelabs and haven't found a good coin or relic in quite awhile.

One day while trying to show a friend how to use my Sov, I had the sensitivity turned down to minimum and when demonstrating a slow sweep I dug a coin sounding target. Dug out this 1898 Ceylon coin from just an inch deep. We were asking ourselves how could we have missed such a "surface" coin?
[attachment 19637 1898ceylon.jpg]

This wasn't a particularly trashy site but there were underground electric cables. The curious thing about this site is that our detectors didn't exhibit any erratic behaviour associated with electric interference or of unstable operation due to too high a sensitivity.

Late last year I returned to the same site with the Quattro. Decided to turn the sensitivity down to about an 8-9 (probably a 12-14 on the EXII) and dug another repeatable coin target - a 1940s nickel and at no more than two inches deep!
[attachment 19638 1940nickel.jpg]

 

[TigerNed]

I was wondering, would you mind sending me those maps or a link to them, of the watchtowers in the Cebu area?...

I won't be going back this year, but will be going in 2007.

I now have a house I built in Toledo City, Cebu. Hopefully someday you can visit me there, or maybe I can make it up to Manila..


Thanks, Ned......

PS: I lost that nice Christmas picture of you and your wife also when my computer blew-up....

 

[Doug[Manila]]

Hi Tiger Ned,
I remember that... did you get to hunt any of the forts that I sent you? I will have to look for that book though as I may have lent it out to a friend in Bacolod. If that's the case, will have to wait for when he comes up to Manila or I do a biz trip in his area.
Take care,
Doug

 

[TigerNed]

Hi Doug,

No I didn't get to do any my last trip, but the trip before I was guided to a Camp site where Japanese Troops stayed during WWII.

Their pill boxes where still intact and even a couple of stone pilled fire pits where there to be seen.

I found lots of ammo casings and one religious medal...

some japanese china also, but that was all broken into pieces.

Never got to hunt any watch towers....I'm hoping to get the chance next time.

Nice to hear from you, and I hope you can find those maps, they where very interesting..

Ned

 

[beachguy777]

I gotta argue with you on this one. My understanding is that if the sensitivity is set too high (manualy) you'll get eratatic behavoir or chattering of some sort., but if you weren't getting any of that, how in the world couldn't the Quatro pick something up that shallow, unless you had it notched out somehow with discrimination before. That's the only way, I believe that you may not have found those coins before. My understanding is that the only thing lowering the sens setting does is reduce the depth detection, so that wouldn't make sense. I'm certainly open to arguments or discussions on this, but "that's my story, so to speak, and I'm stickin' to it" unless you can convince me otherwise.:|:O:|

 

[Doug[Manila]]

Hi Beachguy,
I won't argue with you or convince you as I am not sure why the Quattro or Sov at high sens cannot find coins these shallow except to say that the higher sens sees too much and this masks the shallower good targets. I am able to tell the erratic falsing on my Sov better and this gets me to lower sens. But somehow my Quattro does not give any erratic signals or falsing...
Coins these shallow can be easily found with any detector if their sens is low enough but I can tell you that I have been through this place even with my Tesoro and the four inch coil which is my trashy site relic unit and it missed these two coins.
All I can say is that there's probably more to what we know in terms of electric cable interference...some of them are pretty obvious but not the ones in this site.
So that's why I say higher sens can mask...

 

[Doug[Manila]]

nthought we lost you for a week or two...welcome back and we missed ya!

 

[Charles (Upstate NY)]

I think only the Minelab engineers could explain this one but I have seen the same thing with the Explorer many times on the beach. I'll have the coil right on top of a shallow quarter and get at best an almost not there signal, the break in threshold gets my attention. Then I raise the coil up a few inches and the quarter is blasting my headphones off.

 

[mtdoramike]

But to me, it's with the 10" stock DD coil. I haven't noticed it with the 8" concentric coil.

 

[Angela (Australia)]

This is a very interesting line of questioning because of what I've experienced detecting on the goldfields here. I have to agree with you Beachguy, that if the sensitivity is too high, you can get falsing and chattering from the detector, because it's trying to read too much at once, particularly in very trashy or mineralised ground. But even with the sensitivity on low, say +9 or +10. I have found that some old coins buried just below the surface were not read by the detector initially until I went back and raked a site, or it rained and ground conditions changed somewhat, and for some of those coins, which would normally give me a definite positive number reading, were giving me negative number readings, even the tones changed. But one thing I DID notice with regard to all this, is that the target was DIFFERENT than the others, in that it was slightly worn, or had a hole punched through it, or was rust stained from other targets in contact with it. I don't believe for a minute that Minelab could have covered all of the intricate senarios that the Quattro will have been exposed to, with regard what the detector will, can and won't do in these situations.
Cheers Angela