Some preliminary Correlate testing

[earthmansurfer]

I've done just enough testing in the field to think that correlate mode may cause me to miss some smaller coins. Two programs I've run with correlate occasionally missed some small coins (checking by switching programs). But the iron is a nightmare by this 500 year old castle I hunt by so I thought to continue to investigate it as a partial solution to falsing and just working in iron in general.

I don't know if air testing is at all valid for testing the correlate function, but considering the coins I sometimes encounter (very small and thin) the results got me thinking. Please see the below picture for a coin size comparison. I tested a dime sized hammered coin (weight .8 grams), a dime (2.3 grams), a Nickel and an old large Kreuzer. I used two small very rusty nails (one with a square head). Note how light that hammered coin is. 1/3 the weight of a dime with the same diameter.

Settings:
No discrimination (iron at -5 tone)
Sens 6 to 8 range
Disc 80 to 90 range
Filters - 5 Band
Recovery 42 to 60 (Below 42 and the targets broke up badly. Above 60 ish and I would miss the hammered)
Correlate - When used the span was at 45 or so. (I moved it so high up as to turn the span off - no change in air testing).
Wrap - I have it at -94 but won't really find coins up in the 90's here, so don't worry much about this setting.
I was swiping the coins around 4" in front of the coil.

Swiping one coin at a time around 2"-3" from the 2 nails together, I could hit all of them at the recovery range above in BEST DATA with the nails present from 1/8" to 12". VDI's without nails were as follows: Hammered 16, Dime 75, Nickel 19, Kreuzer 79, nails -48 to -60 ish
VDI's with the nails were as follows: Hammered 2 to 12 range, dime - all over but mostly near 70's, Nickel - 14-15, Kreuzer 70's

Swiping a coin as before but in CORRELATE, the following was observed.
VDI's without nails were as follows: Hammered 16, Dime 78, Nickel 17-19, Kreuzer 80 - 82 (I find it interesting that the VDI are slightly moved)
VDI's with nail were as follows: Hammered no, Dime 78, Nickel no (but sometimes heard a pos tone), Kreuzer 70's

The good news is that in Best data I feel VERY confident hunting in small iron. The V3i hit every combination with the nails (but lengthwise of course). I can drop my Rx around bigger/deeper iron.

I think what I'm dealing with is that a small hammered coin might be too small to reliably search for in correlate??? You UK guys should do some further testing if possible. I know some of you have guys in The States found Nickels in Correlate and around trash though. Any ideas here?

Thanks,
EMS

 

[Rob (IL)]

Sorry but this really needs to be answered by UK guys. My correlate program is not close to yours. My gains are much higher and recovery much longer. Of course we don't have hammered coins. That's why I think it is crazy for guys to not realize that what works for me isn't necessarily what will work in your soil. I'm sure your countrymen will be along soon. ROB

 

[earthmansurfer]

Rob but as I said I also couldn't read a Nickel (though it's bigger but with a low VID like a hammered). This also was observed with the Nickel I buried in my yard. I'm wondering what others have observed with in the ground correlate testing with Nickels around iron in particular.

It seems though that even when run correctly, the correlate program narrows down the acceptable range of target signals two two frequencies. That may get rid of trash more often than not, but there is still the "not" to consider. I don't have high mineralization (I have low) but do have loads of decomposing iron, so correlate is applicable.

Is the only difference to running and not running correlate that I might get more falses not running it? I mean it doesn't seem to enhance signals. Anyone? UK guys?

 

[Rob (IL)]

Is the only difference to running and not running correlate that I might get more falses not running it? I mean it doesn't seem to enhance signals. Anyone? UK guys?

The correlate program doesn't enhance signals, it just helps to eliminate signals from the iron. This has to do with with the iron signals varying enough that they don't fit within the span limit. This is the same reason it helps with EMI problems.