I tried a test today using settings 70 sens. 55 discrim and 2+ an iron nail was not picked up as a grunt but a small 3rd century roman coin was. I them placed a KGV halfpenny right under the iron. No iron grunt but the coin came through load and clear. This was on my drive and not in the field it is still too cold out there !! interesting though
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High Iron discrim
- Thread starter Youngted
- Start date
Do Jabbo's test.
I've set that test up with all but one of my detectors (haven't done the newest one yet but have proven to myself that it does not defy the laws of physics).
Raising a discriminated out target directly above a good target by 4 to 6 centimeters, then offsetting it some and seeing what happens just about makes the case for running in all metal and digging it all if you are in a location that is highly likely to have good targets. Only almost, because there are areas I hunt that have so much trash that I could spend years digging it all in a 50 meter by 2 meter area next to a foot path and still not put a dent in it.
That's why smaller coils, working slowly, and searching an area from different directions help significantly, but don't solve all masking issues.
Cheers,
tvr
P.S. What detector are you using?
I've set that test up with all but one of my detectors (haven't done the newest one yet but have proven to myself that it does not defy the laws of physics).
Raising a discriminated out target directly above a good target by 4 to 6 centimeters, then offsetting it some and seeing what happens just about makes the case for running in all metal and digging it all if you are in a location that is highly likely to have good targets. Only almost, because there are areas I hunt that have so much trash that I could spend years digging it all in a 50 meter by 2 meter area next to a foot path and still not put a dent in it.
That's why smaller coils, working slowly, and searching an area from different directions help significantly, but don't solve all masking issues.
Cheers,
tvr
P.S. What detector are you using?
I did the test many many times in my basement on cardboard boxes. Even an iron thumb tack 4 inches above and 4 or 5 inches to the side will mask a silver quarter completely. Six inches off to the side seems to be out of range of the coil, sometimes. Gotta sweep approaching the coin then toward the iron piece to get some kind of a signal, approaching the iron first will knock out the coin. The coin can be detected easy if a small iron piece is level with the coin and very close, but not when they are separated by a few inches and especially if the iron is higher than the coin. Using a small coil didn't do better than a larger one.
Jabbo,
Did you change up sweep speed?
My testing indicated that if I slowed the sweep down, I could uncover the good target about the width of the coil from the masking iron when the iron was well above the good target when I swept across the the iron first. When I swept across the good target first, it was about half the coil's width before I'd get masking affects, starting with a broken beep or short chirp before disappearing. Seemed to be about the same with concentric and DD coils although a couple of coils on other than Tesoro's were a little further out. They are also the coils that I can't seem to get close to any play ground equipment posts; so I think they spread the electro-magnetic field a bit.
Pretty much the faster the detector recovers, the quicker I could sweep, but still was sweeping slower than my normal leisurely hunt speed to get the best un-masking. If I know I'm in trashy ground, I make a conscious effort to slow down.
tvr
Did you change up sweep speed?
My testing indicated that if I slowed the sweep down, I could uncover the good target about the width of the coil from the masking iron when the iron was well above the good target when I swept across the the iron first. When I swept across the good target first, it was about half the coil's width before I'd get masking affects, starting with a broken beep or short chirp before disappearing. Seemed to be about the same with concentric and DD coils although a couple of coils on other than Tesoro's were a little further out. They are also the coils that I can't seem to get close to any play ground equipment posts; so I think they spread the electro-magnetic field a bit.
Pretty much the faster the detector recovers, the quicker I could sweep, but still was sweeping slower than my normal leisurely hunt speed to get the best un-masking. If I know I'm in trashy ground, I make a conscious effort to slow down.
tvr
Shenandoah Digger
New member
Another perfect example disproving the myth of iron see through. Even with the iron discriminated out, the good target will not respond. That's because the disc'ed out target in fact does respond, but the user has told the machine not to report it with an audio beep, by setting the disc above the conductivity of the target. No need to say that this or that machine can see through the iron. It can't.
tvr said:Jabbo,
Did you change up sweep speed?
My testing indicated that if I slowed the sweep down, I could uncover the good target about the width of the coil from the masking iron when the iron was well above the good target when I swept across the the iron first. When I swept across the good target first, it was about half the coil's width before I'd get masking affects, starting with a broken beep or short chirp before disappearing. Seemed to be about the same with concentric and DD coils although a couple of coils on other than Tesoro's were a little further out. They are also the coils that I can't seem to get close to any play ground equipment posts; so I think they spread the electro-magnetic field a bit.
Pretty much the faster the detector recovers, the quicker I could sweep, but still was sweeping slower than my normal leisurely hunt speed to get the best un-masking. If I know I'm in trashy ground, I make a conscious effort to slow down.
tvr
TVR,
Have you checked your detection depth when using a slow sweep in disc mode? If not, you should. It may send you back to areas youve already searched.
Ism,
Yes, with most of the detectors that I have, depth gets a little better going slower. I re-hunt most of the places I've been to. Keep telling myself to slow down and only work a small area during each return trip. By the end of many hunts, I've picked up a little more speed and lost most coil overlap, or even broken into a random hunt pattern.
The good news is that as I get older, I am slowing down. Possibly a blessing in disguise.
tvr
Yes, with most of the detectors that I have, depth gets a little better going slower. I re-hunt most of the places I've been to. Keep telling myself to slow down and only work a small area during each return trip. By the end of many hunts, I've picked up a little more speed and lost most coil overlap, or even broken into a random hunt pattern.
The good news is that as I get older, I am slowing down. Possibly a blessing in disguise.
tvr
tvr,
In testing my Vaq and Cortes, I discovered that a brisk (not fast) sweep will increase detection depth by as much as 2" over a slow sweep when discrimination is at max. This phenomena decreases rapidly as the disc is reduced. My theory is that a slow sweep in high disc, doesn't induce a rapid enough phase shift for the detectors liking....but that's a wild guess. I can only testify to the two above mentioned detectors. My TDI loves "slow-n-low" however its a PI machine.
In testing my Vaq and Cortes, I discovered that a brisk (not fast) sweep will increase detection depth by as much as 2" over a slow sweep when discrimination is at max. This phenomena decreases rapidly as the disc is reduced. My theory is that a slow sweep in high disc, doesn't induce a rapid enough phase shift for the detectors liking....but that's a wild guess. I can only testify to the two above mentioned detectors. My TDI loves "slow-n-low" however its a PI machine.
Interesting results with high discrimination. Had not tried that scenario.
I almost never run discrimination higher than middle of the foil range except when thumbing to get ID information. I usually run middle of the iron range to low end of foil depending on the trash that is around.
I almost never run discrimination higher than middle of the foil range except when thumbing to get ID information. I usually run middle of the iron range to low end of foil depending on the trash that is around.
Yeah tvr, I believe around the foil range the depth/speed equalizes . Now one thing I haven't considered is the surrounding trash and how it affects depth. A brisk sweep would likely miss a deep object under those conditions, maybe a slow sweep in areas like this would help more than hurt since surrounding trash greatly affects depth, there may be a trade-off