Discrimination and Depth

[BamaBill]

I know that one of the ways people identify targets, using tone only machines, is to thumb the discrimination knob until they lose the target. What I want to know is if anybody has performed an in-air test where they also changed the discrimination level to see how much it changed the potential depth? I've proven to myself in the field that discrimination does rob a machine of depth. Accepting that premise we really need to know how much change there is in depth, because if the target you are identifying this way is on the edge of your depth, you will lose it as soon as you start thumbing the discriminator and you'll assume it was junk.

 

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[Charlie P. (NY)]

Lets discect this.

For maximum depth you should be properly ground balanced? True/False.

If salty soil balances at 35 and magnetite soil balances at 80, what is the G.B. setting for air?

Forget the air tests. Hit a target in the soil on low discrimination and then do your adjustments. Take a few notes. Then dig the target. Or bury a nickel at 7" or 8" in your yard and see what gets you good & consistant readings on that. Put some coins beside or below nails and pull-tabs while you're at it.

There is nothing in the air to discriminate against. In certain soil (and with certain detectors) a small amount of discrimination will be deeper than all metal. That's a trait of the Musky and I assume there are other units that share this quirk.

Some units link the gain to the discrimination, figuring the user that is heavy handed on the discrimination doesn't want to hear anything but the solid beeps of good coins.

 

[BamaBill]

Good point Charlie about this test has to be run with a target in ground, because of the GB thing. I think I'll add a few targets to my test garden and then try this particular test to see at what depth and discrimination levels I start losing targets with my Tesoros. I don't know if this going to be something to check with the MXT, since I don't change the discrimination while in the field.

 

[findit]

bama you brought up another good point. if you get a target on the edge of your depth and you disc to see what it is, do you lose it because of what it is or do you lose it because of depth. in other words you might have a silver coin but lose it on foil setting and move on, not knowing that it disced out becuase you lost it on depth. so for this reason i like to dig everything. does this make sense to anyone else?

 

[BamaBill]

Yep findit, that is exactly the point I was trying to make. I guess what I need to do is establish at what depth different levels of discrimination will respond and work from there. When I'm relic hunting with my Tesoros I usually just turn the discrimination to or slightly above Iron and then dig anything that doesn't noticeably break up the signal. This has been pretty reliabe, since at new sites I'll usually start out by digging everything and I've found that everything that breaks up (to my ears) has been junk. When I've got a hotspot (bullets or identifiable CW relics) I will start hunting in all metal. This can get problematic in a junky area, but to me its worth it if I come out with a couple of choice pieces somebody missed because of all the junk.

 

[bjw]

ground matrix can change so I'm not certain if predetermining at what depth a target will be lost with increased discrimination would be conclusive in all areas. Any target that is deep basically needs to be investigated if it appears to be the correct size.
BJW

 

[JOE(USA)]

BamaBill,

We all have our methods of detecting, so I'm not saying my way is better,but here it is: I only use angle of attack and height of coil above ground to listen for changes in target sound. If using a dual disc. circuit like the Tesoro Tejon I go DOWN in disc. with the second circuit. I listen for subtle changes in the target sound. The reason for only doing this with a dual discriminator is that I know EXACTLY how much rejection I have dialed in to both circuits. I would never just roughly thumb in more discrimination. I NEVER check the target with MORE discrimination. Joe