A 1971 Memorial Cent Taught Me Something About My Equinox....

AirmetTango

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...I’m just not quite sure what I’ve learned yet :?::?:

In an effort to teach myself a little more about how the various settings on the Equinox work and interplay with each other, I’ve been doing some experimenting on my last few hunts with different modes and settings, and cross-checking targets in the wild before digging.

I was hunting a curb strip earlier today, primarily hunting in a modified Park 1 and cross-checking certain targets in a modified Field 2 using the stock coil (I’ll detail the settings of each mode below). As I hunted, I was finding that both programs where able to hit all of the compared targets regardless of depth and with similar VDI numbers. But to my ear, the Field 2 program seemed to add a little stability to each of the signals. It’s hard to describe in words, but the tones just sounded smoother and the VDI seemed less jumpy. Admittedly, that may just be comfort and familiarity bias - I’ve been using Field 2 set up in a similar way a lot in my farm field permissions lately.

But then about 1.5 hours into the hunt I got over a nearly perfect sounding 25-26 tone while swinging in the Park 1 program. I switched over to my Field 2 program, expecting the same comparison results as the rest of the day...and I was astounded to hear absolute junk! Numbers all over the map, and tones to match. I switched back and forth to each mode again, and circled the target each time....Park 1 program said “you MUST dig this target” despite a little variability as I circled, but Field 2 said “there’s absolutely nothing interesting here...don’t waste your time, move along”.

So of course I had to dig it...and from only 5” down, I popped out the 1971 copper memorial cent. Ok, ok...I know some of you are saying Field 2 was right :lol: But this could easily have been a keeper target that the Field 2 program was about to have me walk over without a second thought. Sure, that happens sometimes, but it’s a real head scratcher when Park 1 was not fooled at all and emphatically said “DIG”. To my eye, the settings aren’t too drastically different. In Field 2’s defense, rooting around in the hole a little more turned up a piece of trash that rings up as a mid-tone so there was definitely some pollution in the hole that clearly was affecting the signal. But the Park 1 program almost ignored it.

This is the first and only target I’ve encountered with such a drastic reporting difference between two modes in my limited time actively comparing signals. For the rest of the hunt today, all subsequent signals went back to comparing reasonably well.

So here are the settings (hopefully it will format ok):

Mode: Park 1
Noise Cancel (auto): 9
GB: 0
Volume: 25
(T1) 2
(T2) 25
Target Tones: 50
(T1) 1
(T2) 25
Accept/Reject: -9 to 0
(T1) -9 to 0
(T2) 1 to 40
Recovery: 6
Iron Bias: 2
Threshold: 0

Mode: Field 2
Noise Cancel (auto): -8
GB: 22
Volume: 25
(T1) 1
(T2) 25
Target Tones: 50
(T1) 1
(T2) 25
Accept/Reject: -9 to 2
(T1) -9 to 2
(T2) 3 to 40
Recovery: 5
Iron Bias: 1
Threshold: 0

Other than the obvious mode difference, the only major difference is ground balance, which admittedly was a mistake. I intended to have both machines at 0, but accidentally left Field 2 on its ground balance from earlier in the hunt and didn’t discover the difference until later. Hard to imagine the ground balance would make that big of a difference - plus Field 2 was the one actually balanced to the site anyway, so you would think it had the edge! There are also some minor differences in recovery speed and iron bias, but it’s doubtful either of those created the situation.

Anyway, I guess I’m looking for ideas on what others think might have caused such a big difference between the two modes. I have been absolutely in love with Field 2 in my farm fields, but it looks like it might be worth my while to re-hunt in Park 1!

Here’s some shots of the offending Memorial cent (yep, I cleaned it! Wanted to see if there was any pitting or corrosion that might explain the different signals) and it’s buddy from the hole:
 

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I'm almost certain that bad ground balance in "FIELD" IS the culprit.

Changes in ground balance can directly affect the ID number you see on the screen.

How did you happen to get GB22 in field mode instead of something near 0? Did you possibly GB over a target before swinging; or was it set from another location?

I know if I set GB tracking to ON in my area and am hunting in a very trashy area, multiple swings in certain spots can get my GB way off from where it should be in a very short period of time.... with missed Id results similar to yours..... and that's why I don't use the gb tracking anymore.
 
I'm almost certain that bad ground balance in "FIELD" IS the culprit.

Changes in ground balance can directly affect the ID number you see on the screen.

I would be willing to believe the ground balance difference could be the cause, but I don’t understand why it only skewed the numbers on one target. All the other targets I compared before and after this one matched pretty well to each other - and there were several other copper penny comparisons that I made, so theoretically that rules out differences in composition. I would think that all of the Field 2 numbers would be skewed if GB was the problem - or at least all of the copper penny numbers?

How did you happen to get GB22 in field mode instead of something near 0? Did you possibly GB over a target before swinging; or was it set from another location?

I had done a manual GB in Field 2 near the start of the hunt, but forgot to reset it back to 0 when I decided to do direct comparisons between the two modes. I performed the GB the same way I usually do: I set my sensitivity, noise canceled, then activated the “horseshoe” button to turn off all discrimination so I could hear everything. I swung over the ground until I found a spot with no tones and no VDI reading, then went into GB and pumped the coil until the numbers stabilized. Using that method, I typically see numbers between 5-35 in my area, so 22 is not really unusual.

I know if I set GB tracking to ON in my area and am hunting in a very trashy area, multiple swings in certain spots can get my GB way off from where it should be in a very short period of time.... with missed Id results similar to yours..... and that's why I don't use the gb tracking anymore.

Exactly. To be perfectly clear, GB tracking was not on, and I never use it for the reasons you mention. I’ve read in multiple credible sources that a significant drawback to tracking is that if you swing multiple times over a faint target, the tracking feature can start to interpret the weak signal as part of the ground matrix, and changes the GB accordingly - effectively removing the signal. Deeper targets literally disappear.
 
So why not try Park2 over it? For the record I use Park2 with 5 tones pretty much exclusively because I found it to be the best all around for me. I could be shooting myself in the foot and maybe I need to get out of my box a little more and go back over places in other programs. Is there a reason you are not using Park2? Do you find 50 tones a plus for deciding what or what not to dig?
 
If the issue was only with a single target and other targets correctly id with identical settings, then it would appear that it is not the detector, but the ground at a single spot that caused the good/bad target error.
Could it possibly be that the extra metal (looks like a crushed bottle cap) in with the cent was swinging the id? I know of no way to determine that after the fact.
I do know that bad ground balance can cause loss of sensitivity/ rejection of good targets as well as loss of depth.
 
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Is there a reason you are not using Park2?

No real reason other than Field 2 is what I use a lot in my farm field permissions, I'm very comfortable using that mode, and most of the settings (tone pitches/volumes, etc.) had already be modified to suit my preferences. My understanding (which could easily be wrong) is that the main differences between Park 2 and Field 2 are presets more so than frequency weighting. One place I've seen this mentioned is Steve Herschbach's post on his DetectorProspector forum. It's not anything official since Minelab doesn't publicize the frequency weighting, but Steve's opinion holds a lot of weight with me - he was a pre-release field tester for the Equinox.

Anyway, my goal for the hunt was simply to experiment with Field 2 in a curb strip vs Park 1, which has been my usual curb strip mode. In hindsight, maybe I should have taken the time to hit this particular target in all modes, but at the time I was just too curious about what was in the hole that was creating such a difference.

Do you find 50 tones a plus for deciding what or what not to dig?

Yes, I've quickly learned to really prefer 50 tones. For me, the extra tones gives me much more information about the potential target. For example, a noticeable "flutey" or "warbly" quality to a high tone - likely junk/can slaw/bottlecap.
 
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My thought from looking at the settings difference is a combination of recover and iron bias. Field one shows recovery of 6 and iron bias of 2. Field 2 shows recovery 5 iron bias 1. We are talking about one particular hole and assuming the same swing speed for both settings. A swing speed of 6 matched your recovery setting better for this exact hole with the trash nearby. Field one allowed the detector to interpret two individual signals. In field 2 your swing speed was probably to quick for the setting of 5 to do its job of separating the targets well. As for iron bias I see it that software interpretation sees a more inconsistent/bouncy/iron like signal and with the lower iron bias it is more likely to tell you “iron” than good signal. The slower recovery speed in field two only exacerbates this problem as compared to field one.

The other holes and signals just didn’t have a piece of trash close enough to cause the problem of a suspect signal that gets “ironed” out by the software maybe? Did you swing slow and fast over this target with both settings? Maybe a slow swing in field 2 in order to match the 5 recovery would have given a more solid signal?
 
My thought from looking at the settings difference is a combination of recover and iron bias. Park one shows recovery of 6 and iron bias of 2. Field 2 shows recovery 5 iron bias 1. We are talking about one particular hole and assuming the same swing speed for both settings. A swing speed of 6 matched your recovery setting better for this exact hole with the trash nearby. Park one allowed the detector to interpret two individual signals. In field 2 your swing speed was probably to quick for the setting of 5 to do its job of separating the targets well. As for iron bias I see it that software interpretation sees a more inconsistent/bouncy/iron like signal and with the lower iron bias it is more likely to tell you “iron” than good signal. The slower recovery speed in field two only exacerbates this problem as compared to Park one.

The other holes and signals just didn’t have a piece of trash close enough to cause the problem of a suspect signal that gets “ironed” out by the software maybe? Did you swing slow and fast over this target with both settings? Maybe a slow swing in field 2 in order to match the 5 recovery would have given a more solid signal?

Thanks for those ideas, Wloch - I modified the quote above to correct Field 1 to Park 1 to help avoid confusion, but I think you’ve probably hit on the right answer. Surprising that such a small change in both RS and IB combined to create such a big difference in target reading, although I’m sure that the other factors helped to create a “perfect storm” situation: differences in mode (frequency weights) and GB, along with the different RS and IB, plus the extra metal in the hole all combined to create a junky signal in Field 2.

Good point about swing speed. I’m sure I used the same swing speed in both modes, so that wasn’t helping Field 2 with the lower RS setting. In fact, in hindsight, I’m pretty sure at some point during the comparison I probably sped the sweep up - making tight, relatively fast passes over the target - which would have put Field 2 at even more disadvantage during the comparison.

Regardless, I think that dig taught me a valuable lesson about how important it is to understand the interrelationship between RS, IB and the rest of the settings. Also important to understand how swing speed might impact otherwise good settings.
 
I run an iron bias of 0 in Park2 recovery 6-7. Wide open screen 5 tones with the iron volume low. Pitch tones are kind of set the way Dirtfishing has his on his tutorial video but, with some modifications. I have more problems with falsing iron in Park1 with the iron bias set low 0-2 so that's one reason I don't use Park1 much (I hunt a lot of places with tore down houses). I will use Park1 in a clean yard though. Like I said I really need to start comparing signals with different programs. This topic is certainly pushing me in that direction.
 
I havent used Field modes in quite some time, but when I did I always thought the tones seemed to have more of a fuzzy sound to them compared to park modes. Not crisp and clean like Park 1. Perhaps I will give it another try.
 
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