9" Round HF Sensitivity To Thin Flat Iron Question

[kac]

Was giving the Orx a run today and came across a jump signal 40's and an occasional low 70's. Iron probability was 0 and I knew it was trash but dug it out of curiosity. It turned out to be the bottom of an old tinned can that is all rusted. When I layed the can end flat out the Orx could not detect it in any of the coin modes and it would sound off in the gold modes but give no number.

Tested the can end when i got back home. AT Pro gave a solid grunt and low numbers, Multi Kruzer was spot on with iron sound also. The Tejon also was able to crackle when disc one set on the iron line.

I kept the Orx coin modes and first 2 gold modes stock settings including disc at 7. Not sure why the Orx can't see the can end.

Bottom line is if I am running in a disc mode and come across a piece like this I could easily miss a good target below as it may be a masking problem. Has anyone else noticed this?

[Chase Goldman]

Do you have iron volume on?

[kac]

Yes I always have iron audio on.

[Jeff McClendon]

7 hours ago, kac said:

Was giving the Orx a run today and came across a jump signal 40's and an occasional low 70's. Iron probability was 0 and I knew it was trash but dug it out of curiosity. It turned out to be the bottom of an old tinned can that is all rusted. When I layed the can end flat out the Orx could not detect it in any of the coin modes and it would sound off in the gold modes but give no number.

Tested the can end when i got back home. AT Pro gave a solid grunt and low numbers, Multi Kruzer was spot on with iron sound also. The Tejon also was able to crackle when disc one set on the iron line.

I kept the Orx coin modes and first 2 gold modes stock settings including disc at 7. Not sure why the Orx can't see the can end.

Bottom line is if I am running in a disc mode and come across a piece like this I could easily miss a good target below as it may be a masking problem. Has anyone else noticed this?

In the gold modes, the Disc IAR settings of 2 or more may breakup or completely null out rusty tin near the surface.

In the coin modes too, it seems that some flat rusty tin has an ID that is somewhere between 99 and 0 and most often gives me -- for an ID and basically nulls out the background chatter or threshold tone if you are using one.

Small rusty tin flakes the size of a US quarter or less can be a real nuisance gold prospecting in the ORX and Deus Gold programs. With disc IAR off they sound very much like a gold or non-ferrous target. With disc IAR on, they will null the threshold and mimic a very deep or very small non-ferrous target that is just barely disturbing the threshold tone with no ID most of the time.

[kac]

Stacked quarter test my Multi Kruzer and AT Pro both dropped to iron range at 3 quarters. The Tejon held the tone to 3 quarters but gave a broken signal just above the iron mark (something I would dig) and the Orx gave a non iron tone to 9 quarters.

The can disapears with or without IAR and I only seem to have IAR option under gold modes and haven't found it useful so it's been off. The can bottom responds the same across the gamut of frequencies and thinking because it is so thin it is just acting like a mask. Only reason I dug it was because in the ground it was on edge and gave a funky signal but oddly no iron signal.

Seems like the HF has little or no fall off on the tip or tail of the coil. Not that it is a good or bad thing, just different and more precise so using tip off to help id iron isn't as reliable for me in this case.

[EL NINO77]

Kac ... remember that in XP ORX the Coin Deep program has a fixed default Silencer / iron bias / to the lowest value ,,,, while the Coin Fast program has a fixed default silencer value somewhere around the value 3 ... so in practice when using the program Coin Fast you hear significantly fewer false signals from iron ...

Yes, the Coin Deep program is deeper, but the Coin Fast program can prove to be a very effective program in separation practice.

 Use the frequency 14.4 khz first .... it gives the least false signals on the iron .. higher frequencies 31 khz and 54 khz I will falses on the iron a bit more ..

Another thing is the limit of discrimination of iron / coke / color / ... it is somewhere at the level of VDI 25-26 ... but in the programs it is set to 7 by default ... which is relatively low ... so you have a sufficient reserve for increase of discrimination up to the level of 25 VDI or higher, because the small aluminum foil also gives 37-39VDI.

Some iron in the ground can also give VDI 97-99- so in detection you can ignore such signals ,, -mainly after checking with a pinpoint detector..or checking the target with a coil from a different sweeping angle ...

 Gold and Fine gold programs are allmetle programs with another type of Discrimination * It is called IAR discrimination - which works differently from classic discrimination ...
 so you can use Gold programs with a high setting of 4-5 IAR to check for any suspicious coin size signal ...
For very small targets, you already need to be more careful when using the high setting of 4-5 IAR because .. it can signal some targets to you as a small iron ..

...the most important thing is to reduce IAR discrimination when you are in more mineralized terrain ...

[kac]

I have kept IAR off as I was affraid it might kill the signal on small thin silvers like trimes or deep coppers as I was not sure how it works and want to keep the machine as close to stock settings as possible. I did however use 15.6 khz instead of the 14khz so it plays nice with my Profind 35 pointer.

I did dabble with increasing the discrim up to 14 to widen the gamut when responding to iron in items like washers and bottle caps but that has not proven consistent. I noticed that it's response to large flat targets like flattened cans can ring high and large iron can spike to the high 90s so I have been doing the usual lift of coil check and also a slow steady sweep to judge target size.

+++++++++++++++++++++++++++++++++++++++

Quick test and pics in my yard with the can end of death. Note the ground itself has a low phase but with the can below the mineralization meter gets pegged but I still have no iron audio.... Programming bug?

This is a coin deep mode at 15.6 khz

[EL NINO77]

Gold programs ....ORX... such as the sound of iron depend on the use of IAR discrimination ..., but in Coin programs ... everything below the discrimination limit has the sound of iron.

 

[kac]

Point I am making is the target that is iron and shows and sounds like iron on ALL my machines except the ORX.

On the ORX is is showing as ground phase which tells me that there is probably an error in their programming where or the machine is not sensitive enough to pick up on the target as being an object.

Bottom line in the real world if there was a descent target near or under that flat bit of iron it would be missed by the user because it is masking without any audio response. If I hunted in all metal the sound is offset from the target much like magnetite does.

I would rather hear iron than totally miss the target through silence and just see a phase meter bounce up...

[schoolofhardNox]

3 hours ago, kac said:

Partial quote:

Bottom line in the real world if there was a descent target near or under that flat bit of iron it would be missed by the user because it is masking without any audio response. If I hunted in all metal the sound is offset from the target much like magnetite does.

 

Oh..... you should try that. I would be curious if it actually did mask the good target if there was one. If it hears the good target, maybe that glitch is what we have been praying for, in not responding to iron but hearing something good under or near it. 😄 You never know.