Help With Equinox Ground Noise

[GB_Amateur]

13 minutes ago, Jeff McClendon said:

Lowering sensitivity for example from 22 to 18 while in Multi to help alleviate EMI does not result in massive amounts of depth loss where I am.

(Sorry if I've asked this before, particularly if you've answered.)  Do you think this is because turning up the gain also amplifies the ground noise?  I've wondered if rather than these two effects being equally magnified, that turning up the gain (sometimes) actually increases the ground signal compared to the intended target signal.  Same question with iron targets (e.g. nails) relative to non-ferrous targets.   That's something I need to play with in my test setup when I get it cleaned (but waiting for warmer weather).

20 minutes ago, Jeff McClendon said:

Changing to a single frequency that is not bothered too much by EMI and keeping my sensitivity at 22 doesn't result in the same depth capabilities as staying in Multi, in fact I lose depth capabilities and the enhanced ability to hit poorly oriented or partially masked targets. Also, target ID completely goes out the window here and all deeper non-ferrous targets give numerical and tone IDs from the mid 20s to high 30s or even 40. So discrimination is pointless and I have to dig everything or risk missing good targets.

Sounds like my experiences but I'm pretty sure my soil is not as 'magntized' as yours -- only half scale on the Fishers.  Using the Equinox, for shallow(er) targets I can get away using single frequency and still get decent dTID's.  But most of my older coins fall below the cutoff where reliable dTID's get lost.

The park I've been detecting this past year is for the most part far enough from EMI that I can run gain of 24 quietly.  (There are exeptions.)  Still I haven't found a coin deeper than 8" or so.  I don't know if that's because there aren't any deeper coins (really doubt that), whether I'm just not getting the coil's deep sensitive zone over them, or possibly I'm getting to the limit the ferromagnetic ground components allow.  But this last point would seem to be inconsistent with the depths you've reached in likely much stronger mineralization.  Sounds like I need to experiment with lower gain....

 

[Jeff McClendon]

This is just my opinion. It may be born out of facts and experiences but I am definitely not an electrical engineer.

The ground itself and EMI are always targets, period.

For fixed single frequency detectors, the only ways to lessen the effects of ground noise (besides ground balancing) and EMI (besides noise reduction adjustments if the detector has that feature) are to lower the sensitivity and/or use a smaller DD coil. If you happen to be detecting with a single frequency detector operating at the wrong fixed frequency for EMI/ground mineralization conditions you may be screwed or you better have a different detector operating at a different frequency handy. For simultaneous multi frequency detectors that are also very high gain detectors like the Equinox, my statement holds twofold or threefold true depending on how many frequencies are being used. Multi IQ will get a great look from multiple perspectives at any detectable target which makes it potentially very accurate but also overly sensitive to all detectable targets including ground mineralization "fog" and "clouds" of EMi.

Lowering the sensitivity a bit using Multi may perform better on coin sized or larger deep targets if the Equinox is too chatty along with slightly adjusting the recovery speed if you have an 800. Also, the Park 1 or Field 1 vs Park 2 or Field 2 setups for deeper targets question is one I haven't been able to answer. I have found deep silver, copper, gold and deep V nickels past 12" in both 1 and 2 modes with sensitivity at 22 or less and recovery speeds that are still on default settings........?

For the absolute deepest detecting or for tiny stuff like micro jewelry and gold prospecting I use the Gold modes in Multi, rely on the target ID numbers and VCO tone aspects while adjusting recovery speed and sensitivity according to ground and EMI conditions.

[Badger-NH]

Going from 20 to 25 on Sensitivity gives me a gain of at least a half inch of depth for each increment.  I think all my single frequencies are deeper than Multi.

I relic hunt in Field 1 almost exclusively because it has shown to be deeper than Park 1.  I mostly use Multi for mineralized ground and iron and prefer the single frequencies for clean ground.

[Jeff McClendon]

Chuck (GB_amateur)

So, I forgot to pose this question which I don't know the answer to but which is at the heart of this discussion even though it is lurking in the background....

Are ground noise and EMI still a factor for target ID accuracy and especially depth, even when they seem to have been "silenced"?

 Is using the Equinox in Multi (which is the way the Equinox was designed to be used optimally according to Minelab with single frequency operation being for diagnostic or emergency use) the best solution for ground noise/mineralization whether silent or audible but not the best solution for bad EMI.

Your example of running at almost max sensitivity using the Equinox in low EMI but ground that is moderately mineralized according to your Fisher F75 makes me wonder.

[Badger-NH]

I've always thought EMI was just noise and that it had no effect on target depth.  I suppose it might interfere with target ID.

[Jeff McClendon]

 

13 minutes ago, Badger-NH said:

I've always thought EMI was just noise and that it had no effect on target depth.  I suppose it might interfere with target ID.

The ground and any physical object may have a dampening effect on EMI but distance from the source to me is more important. A sensitive detector can pick up EMI from buried power and communication lines and from buried wireless transmitters. Plus, the top of the search coil is almost always exposed to any EMI in the area. So, I am not certain whether EMI can effect actual depth or not. Until someone proves to me that EMI has no effect on actual depth (whether I lower sensitivity or not to deal with it in really mild ground for instance), I will leave that as an open question.

[GB_Amateur]

2 hours ago, Jeff McClendon said:

Are ground noise and EMI still a factor for target ID accuracy and especially depth, even when they seem to have been "silenced"?

Good questions, Jeff, and I don't have the answers.  The issue of ground balancing affecting target ID accuracy and depth should/could have been investigated many times over the years.  @EL NINO77 may have done it since he has has performed test stand investigation with soils of different ferromagnetic content.

EMI seems like the more difficult one to investigate since 1) there are so many kinds (from different sources), 2) as mentioned earlier it is both time and space dependent, and 3) having even a single controlled source for test stand investigations seems like an investment that might be out of budget for most detectorists.

We hear a lot of claims/suspicions/feelings about these but particularly with EMI I seldom leave with a confident conclusion after reading those.

You mentioned earlier that using the Equinox's Noise Cancel feature often doesn't solve the problem and I've found that to be the rule rather than the exception for most of my sites.  I.e. In multifrequency I either have EMI pickup and can't silence it with Noise Cancel or I don't (at least don't hear any) independent of what frequency adjustment channel I'm operating.  There have been pleasant exceptions on the former, though.

3 hours ago, Jeff McClendon said:

Is using the Equinox in Multi (which is the way the Equinox was designed to be used optimally according to Minelab with single frequency operation being for diagnostic or emergency use) the best solution for ground noise/mineralization whether silent or audible but not the best solution for bad EMI.

More good questions.  That's the thing about the Equinox -- there are so many (virtual) knobs to turn that figuring out which combination of settings is optimizal for a given site and intended target seems like an impossible task.  I've always done as you and run in multifrequency by default, only resorting to single frequency when I was getting slammed with EMI and forced to turn down the gain more than I felt was appropriate.

This has been a good thread from the start for getting the mental gears turning.  I like these kind of reminders as I have a tendency to get in a 'rut', not changing settings once I find a quiet (EMI and ground balance) group of settings, figuring if it's quiet it must be optimized....  Thanks to all who have contributed.

[Badger-NH]

To me, Multi isn't a magic potion that automatically does everything better.

My experience has been that multi frequency provides no depth advantage in mild ground and using the Equinox in my test garden has helped to confirm that. My tests actually show Multi as having a disadvantage in clean ground.

Multi frequency has the ability to see through bad ground and salt better than single frequencies so there is a point where it will surpass single frequencies but only in ground with a certain level of mineralization.

Generally, if I can run my machine with maxed out settings and not hear any feedback from the ground, I consider it clean and mineral free. That's where I prefer the single frequencies over Multi.

 

[Jeff McClendon]

35 minutes ago, Badger-NH said:

Generally, if I can run my machine with maxed out settings and not hear any feedback from the ground, I consider it clean and mineral free. That's where I prefer the single frequencies over Multi.

 

I have heard this before from some Equinox owners back in the Northeast. I have never had that experience. I have had just the opposite.

So, I am going to guess that a good bit of your detecting is in less modern trashy ground or that you are listening for specific target responses and ignoring others, like a ferrous/non-ferrous choice or a low tone vs high tone choice.

When you are detecting in single frequency with the Equinox in clean, mineral free ground, do you pay close attention to numerical target and tone ID or are you trying for absolute maximum depth where if your Equinox detects a target, you are digging it no matter what the tone or ID might be telling you?

 

[Badger-NH]

53 minutes ago, Jeff McClendon said:

So, I am going to guess that a good bit of your detecting is in less modern trashy ground or that you are listening for specific target responses and ignoring others, like a ferrous/non-ferrous choice or a low tone vs high tone choice.

When you are detecting in single frequency with the Equinox in clean, mineral free ground, do you pay close attention to numerical target and tone ID or are you trying for absolute maximum depth where if your Equinox detects a target, you are digging it no matter what the tone or ID might be telling you?

 

We hunt a lot of woods looking for colonial/early American coins and relics. Much of northern New England was once farmland that has turned to woodland. The ground in the woods is often very clean with occasional iron trash. On average, we might dig a target every 10 or 15 minutes. I dig every signal that I can't absolutely confirm is iron. Most of the targets I dig are iron. We don't see much modern trash at these places. Some farm fields can be pretty quiet too as most have been detected for decades.

I always look at the numbers just for that thrill you get when it's in the 20s or 30s, but I mostly hunt by tone. The deeper a targets is, the better the chance is that I will dig it. Maxed out settings usually means the target ID will not be very accurate on deep targets.

Some farm fields that contain a lot of gravel will be mineralized. We also hunt cellar holes that are surrounded by iron.