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Wayfarer, a little added comment about 'Fold-Over' and Signal Balance.

November 18, 2018 09:50AM avatar
Quote
Wayfarer
I was wondering if you could explain the symptoms of "fold back" while ground balancing, ...
'Hombre' pretty much addressed 'Fold-Over' in his reply. It is a term we have used going back to the early introduction of Ground Canceling recreational-use metal detectors. Generally, most instructions to describe Ground Balance methods only suggest a Positive GB were the Threshold audio increases as the search coil is lowered toward the ground. A negative GB where the Threshold audio drops off a little or completely nulls to silent when the coil is lowered to the ground. And a 'Spot-On' and functional Ground Balance where there is very little or no change to the Threshold audio as the coil is lowered from about 6" to about 1" from the ground.

But there is a 4th effect when trying to adjust a functional Ground Balance and that is what we call 'Fold-Over.' It is very seldom discussed or explained, and some makes/models of detectors do not have a Sensitivity or Gain control for the All Metal mode to allow a user to counter the effects. The cause? The ground mineral content is too severe for the EMF associated with a search coil size and type based on the Sensitivity or Gain control.

'Fold-Over' can be determined by listening to the effects on the Threshold-based audio. If a search coil is held about 6" to 8" off the ground and has a proper, slight audio Threshold hum, the following can occur:

As the search coil is lowered toward the ground, you might hear an audio increase when the coil is perhaps 3" to 4" from the ground, then as you continue to lower the coil, the Threshold audio quickly nulls out and goes silent ... and if you continue to lower the coil closer to the ground, the Threshold audio returns when the coil is very close to the ground. It might sound like a 'normal' Threshold sound to even a slightly louder increase in sound, but this dramatic Increase-Nulling-Increase behavior is referred to as 'Fold-Over.'

For most average hobbyists, who often don't know what Ground Balance is or how to properly GB a detector anyway, it usually isn't much of an issue. That's because they are going to usually be searching in a motion-based Discriminate mode. And whether a silent-search model or one that relies on a Threshold level audio search, the auto-tune and signal processing will generally eliminate the errant signals we might experience.

But if searching in a Threshold-based All Metal mode, especially with no auto-tune or a very slow auto-tune, a Fold-Over condition can present a lot of varied audio responses and behavior, and that is especially troublesome to someone who needs smooth and proper operation for things like Nugget Hunting or even Cache Hunting or Relic Hunting in an All Metal mode.

Many, perhaps most, hobby-based metal detectors have an All Metal mode that doesn't have a variable Sensitivity control. The Sensitivity control, sometimes also called a Gain control, might only be tied in with the motion-based Discriminate mode circuitry. The White's Classic series and most Tesoro models like the Bandido series, have an All Metal mode that is fixed at Full Sensitivity and the variable control is only tied in with the motion-based Disc. mode.

Other makes and models, especially those used for Gold Nugget Hunting, should have a variable Sensitivity control because their searches are usually in the Threshold-based All Metal mode and they need to control the GB so that they can attain smooth operation in a more mineralized environment, especially with rough, uneven ground texture. Some examples of this would be the Tesoro Lobo SuperTRAQ and White's Gold Master series.

With the White's 6000 Pro Xl and XL Pro model, this 'Fold-Over' behavior is handled by use of the Signal Balance control to reduce the receive signal Gain for processing. If you get errant behavior, simply reduce the Signal Balance, very carefully, toward the 'Bad Ground" indication which is counter-clockwise. Then double check in the All Metal mode or Pinpoint function and re-Ground Balance as needed to achieve a nice and proper setting.


Quote
Wayfarer
... and how to know when you have the signal balance turned up too high for the ground you're in. As you know, yn the XL Pro, you can turn up the signal balance too high and lose depth, especially once you get past 2 or 3 o'clock on the control. I just back it off once it starts getting chattery, but maybe I'm still setting it to high and don't know it?
You are correct. If you are working in any area that causes a chattery or noisy behavior, it is best to reduce (counter-clockwise) the Signal Balance ... slowly ... just to the point where it is at the highest setting w/o noise or chatter.

That can be heard as well as seen if the search coil is held at about a 2" height from the ground and the needle is a bit jumpy. Once the needle remains stabile, the Signal Balance isn't set too high. The other way to know the Signal Balance might need a little reduction in setting is when there is a pronounced 'Fold-Over' behavior. A slight variance is still fine for most average searches, but if it is a pronounced Increase then Nulling then Increase, it is best to use the Signal Balance to achieve a best performance setting.

Just remember that a higher Signal Balance is a more enhanced Sensitivity setting and the sweep speed can be at a somewhat slower or moderate sweep rate, but a reduced Signal Balance will require a moderate to faster sweep speed for best in-the-field performance.

Monte

"Your EYES ... the only 100% accurate form of Discrimination!"

Stinkwater Wells
Trading Post

Metal Detector Evaluations and Product Reviews
'How-To' help for Coin & Jewelry Hunting, Relic Hunting and Useful Techniques.

'Regular-Use Detector Team' are models from: Fisher, Nokta / Makro, Teknetics, Tesoro and White's
'Specialty-Use Detectors' are models from: Compass, Garrett and Teknetics
Pinpointers: Using Nokta / Makro and Uniprobe Pointers.
Headphones: Using Killer B's 'Hornet' and White's Pro Star and Detector Pro's Uniprobe ... All w/'tank style' ear cups.
Recovery Gear: Using White's DigMaster digging tool and Signature Series pouch.
Note: Detectors are listed alphabetically by Brand. Models are chosen as desired based on search site conditions.
Some models are assigned for 'Regular-Use' and others are on-hand for 'Specialty Use.'
Additional search coils, mounted on spare lower-rods, are on-hand in my Accessory Coil Tote.


*** All working well today to make memories for tomorrow. ***

monte@stinkwaterwells.com .. or .. monte@ahrps.org
(503) 481-8147
Subject Author Views Posted

How to get the most out of the 6000 Pro XL later it was named XL ProWhite's Electronics

Hombre 101 November 13, 2018 09:16PM

Re: How to get the most out of the 6000 Pro XL later it was named XL ProWhite's Electronics

Wayfarer 69 November 15, 2018 06:22AM

Wayfarer, a little added comment about 'Fold-Over' and Signal Balance.

Monte 45 November 18, 2018 09:50AM

Re: Wayfarer, a little added comment about 'Fold-Over' and Signal Balance.

Wayfarer 47 November 22, 2018 01:42AM

If you have the 6000 Pro XL / XL Pro Instruction Manual, refer to this.

Monte 42 November 22, 2018 08:54AM

Re: If you have the 6000 Pro XL / XL Pro Instruction Manual, refer to this.

Dick Stout 18 December 07, 2018 12:59PM

I dream all the time about going 'back-in-time.'

Monte 21 December 07, 2018 02:58PM

Re: I dream all the time about going 'back-in-time.'

D&P-OR 10 December 09, 2018 01:49PM

Re: I dream all the time about going 'back-in-time.'

Druid 16 December 09, 2018 12:37PM

Re: Wayfarer, a little added comment about 'Fold-Over' and Signal Balance.

Wayfarer 32 November 22, 2018 07:11AM

Darren, you couldn't be closer to describing near perfection. One of White's all-time finest models ....

Monte 33 November 22, 2018 09:13AM

Wonky Ground Balance and Fold Over.....

Hombre 67 November 17, 2018 06:31PM

Re: Wonky Ground Balance and Fold Over.....

Wayfarer 29 November 22, 2018 01:50AM

Re: Wonky Ground Balance and Fold Over.....

Hombre 22 November 22, 2018 11:37AM

Re: How to get the most out of the 6000 Pro XL later it was named XL ProWhite's Electronics

Timbertodd 45 November 14, 2018 07:22PM

Todd, about your '6000' model.

Monte 43 November 15, 2018 05:00PM

Re: Todd, about your '6000' model.

Timbertodd 38 November 15, 2018 07:04PM

Re: How to get the most out of the 6000 Pro XL later it was named XL ProWhite's Electronics

scottwyl 55 November 13, 2018 10:03PM

Re: How to get the most out of the 6000 Pro XL later it was named XL ProWhite's Electronics

Hombre 65 November 13, 2018 10:20PM

Re: How to get the most out of the 6000 Pro XL later it was named XL ProWhite's Electronics

scottwyl 45 November 14, 2018 06:50PM

Two very good models you've added, and a wise decision.

Monte 45 November 15, 2018 05:06PM

Re: Two very good models you've added, and a wise decision.

scottwyl 33 November 16, 2018 01:41PM

Almost .. but not quite.

Monte 35 November 16, 2018 11:53PM



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