Dave Rishar
Silver Member
A situation that I found interesting came up on Saturday. Before I present the problem, let me establish the scenario.
My detecting buddy/girlfriend was using a 9" Deus, running Andy S's trashy park program in 12 kHz. I was using a 11" Deus with the following settings: 4kHz, disc = 1, rx = 2, silencer = -1, with notches from 1-35 and 95-00. Both of us use V3.2 and the backphones. The site in question was a moderately trashy field behind a school dating back to the thirties. The soil wasn't bad, a welcome rarity around here, and we were both running sensitivity at 90 and getting away with it for once. EMI was low for an urban area. My GB was on manual and was at 86 in an 85 area, and I believe that hers was set to tracking.
On our way back to the car, she hit a signal that she liked and began evaluating it. (She tends to spend much more time evaluating targets than I do.) After re-checking at 90 degrees, she pulled out the Lesche and got ready to cut. I asked if I could step in and take a gander at what she had. She agreed. It was reading a slightly bouncy but repeatable 60 for me, and the tone sounded iffy...I don't know a better way to explain it, but most of you probably know what I'm talking about - it was almost but not quite a dig me, with a bit of a scratch or crackle to it. The X-Y showed a "rubber band" instead of a straight line, which for me means that it might be something good, but might be a bottlecap or pull tab. Her X-Y trace showed a line and obviously she liked the tone.
"What do you think?" she asked.
"I'm not sure that I'd dig it," I said. "It could be trash, but I suppose that it could be a zincoln affected by ferrous. It's shallow, so go ahead and dig it. Let's see."
She dug it. It was in fact a zincoln about 4-5" down, directly adjacent to that patch of red grunge one sees when a ferrous object has dissolved into the soil. I was quite pleased that I'd suspected this, but at the same time I was not pleased that she got a good tone/trace and I did not. The big question is, why did this happen? I thought about it quite a bit and we came up with a few theories on this.
1. My larger coil simply picked up more of the ground and got a more distorted signal. I don't personally think that this happened, but it's possible. Or...
2. 12kHz vs. 4kHz. I don't think that the frequency mattered here. If anything, I should have hit it harder and clearer than she did. Or, the one that I'm leaning toward...
3. The disc setting. This one's tricky because I've not yet seen a clear and definitive explanation for how exactly the discriminator works on the Deus, but I'm given to understand that the difference between disc and notch is that the former causes the machine to simply reject the unwanted signals before processing, while the latter processes the signal and then decides not to let you know about it. If this is the case, I can see why we had a different experience on this target - her machine rejected the iron, while mine simply kept it a secret from me. However, her machine successfully discriminated out that rust patch, but mine didn't - I heard a bit of it (that light scratch), and the X-Y saw some of it, making the trace more squiggly and oval-shaped. Is this what happened here?
The possibility of missing a zincoln doesn't bother me by itself, but I'd hate to think that I'm missing other things that I want to find. Air testing didn't show any significant depth difference between disc = 1 or disc = 10, and I'd already been wondering if there was perhaps a reason for why most of the factory programs have the disc up that high. Truthfully, I'd only kept it at 1 on the new program because that's what I'd already been using and it seemed to work, but now I'm beginning to think that turning it up a bit higher would be a good idea.
Thoughts?
My detecting buddy/girlfriend was using a 9" Deus, running Andy S's trashy park program in 12 kHz. I was using a 11" Deus with the following settings: 4kHz, disc = 1, rx = 2, silencer = -1, with notches from 1-35 and 95-00. Both of us use V3.2 and the backphones. The site in question was a moderately trashy field behind a school dating back to the thirties. The soil wasn't bad, a welcome rarity around here, and we were both running sensitivity at 90 and getting away with it for once. EMI was low for an urban area. My GB was on manual and was at 86 in an 85 area, and I believe that hers was set to tracking.
On our way back to the car, she hit a signal that she liked and began evaluating it. (She tends to spend much more time evaluating targets than I do.) After re-checking at 90 degrees, she pulled out the Lesche and got ready to cut. I asked if I could step in and take a gander at what she had. She agreed. It was reading a slightly bouncy but repeatable 60 for me, and the tone sounded iffy...I don't know a better way to explain it, but most of you probably know what I'm talking about - it was almost but not quite a dig me, with a bit of a scratch or crackle to it. The X-Y showed a "rubber band" instead of a straight line, which for me means that it might be something good, but might be a bottlecap or pull tab. Her X-Y trace showed a line and obviously she liked the tone.
"What do you think?" she asked.
"I'm not sure that I'd dig it," I said. "It could be trash, but I suppose that it could be a zincoln affected by ferrous. It's shallow, so go ahead and dig it. Let's see."
She dug it. It was in fact a zincoln about 4-5" down, directly adjacent to that patch of red grunge one sees when a ferrous object has dissolved into the soil. I was quite pleased that I'd suspected this, but at the same time I was not pleased that she got a good tone/trace and I did not. The big question is, why did this happen? I thought about it quite a bit and we came up with a few theories on this.
1. My larger coil simply picked up more of the ground and got a more distorted signal. I don't personally think that this happened, but it's possible. Or...
2. 12kHz vs. 4kHz. I don't think that the frequency mattered here. If anything, I should have hit it harder and clearer than she did. Or, the one that I'm leaning toward...
3. The disc setting. This one's tricky because I've not yet seen a clear and definitive explanation for how exactly the discriminator works on the Deus, but I'm given to understand that the difference between disc and notch is that the former causes the machine to simply reject the unwanted signals before processing, while the latter processes the signal and then decides not to let you know about it. If this is the case, I can see why we had a different experience on this target - her machine rejected the iron, while mine simply kept it a secret from me. However, her machine successfully discriminated out that rust patch, but mine didn't - I heard a bit of it (that light scratch), and the X-Y saw some of it, making the trace more squiggly and oval-shaped. Is this what happened here?
The possibility of missing a zincoln doesn't bother me by itself, but I'd hate to think that I'm missing other things that I want to find. Air testing didn't show any significant depth difference between disc = 1 or disc = 10, and I'd already been wondering if there was perhaps a reason for why most of the factory programs have the disc up that high. Truthfully, I'd only kept it at 1 on the new program because that's what I'd already been using and it seemed to work, but now I'm beginning to think that turning it up a bit higher would be a good idea.
Thoughts?
And 2. 4-8 kHz will hit coins, copper/silver much harder,than the higher frequency's. The next time your out,and find a coin about 6 inches deep,make a pass over it in 12 kHz,and listen to the signal/tone. Then switch to 4 kHz and make another pass over it,and listen to the difference in tone,and volume.Then 8 kHz. You will be suprized! Discrimination kills depth,10 is the absolute highest I will run,and most of the time 8 or lower is the normal setting while coinshooting,if conditions allow it.If you like a quiet machine,with no chatter, Notching is your friend,and cost you nothing in depth. If I'm coinshooting a open area (very little trash) I use a setting of 6 on discrimination,and notch out nothing( I want to hear it all)!
If I was looking for small objects (ear rings,ect.) 12 KHz or higher, would be the weapon of choice! As far a Zincolns go,I have my Deus set to notch out all of them. In our area they look like they have been in battery acid,and are completely worthless. My Deus pays about as much attention to them as it dose to pigeon poop!
