Hub-brain question - Ground balance

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DaveP
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I suspect most of the hub-brain is still asleep but for the little bit that's poked it's head from under the duvet.

Is there any other reason why ground balance is set by moving the coil up and down, other than to have the best chance of finding a clean piece of ground, rather than side to side?

I only ask as my little bit of the HB is working its way through another problem.
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Bors
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When detecting,the Coil is constantly ,even when we do our best to swing at the same distance across the sweep, moving at varying up and down distances. When we lower or raise our coil to/from the ground, it affects the threshold ( back ground hum)which is going on inside the electrical gubbins of the detector . The aim is the keep the threshold steady as you can when we sweep even on an automatic GB detector you initially give it a helping hand at the beginning by doing the Up & down pump routine to get the detector to find its optimum GB position ,so to do that we have to raise and lower the coil for the detector so it can adjust itself to its optimum position of not losing the threshold (which is the important thing)to that ground your Ground balancing to. When you lower the coil the threshold increases, if its positive ground or decreases if its negative ground. The detector does the self adjusting on most detectors these days and also some give you the option of Manually ground balancing if the detector is in difficult ground ,and struggles to GB you can do it manually by small increments ,which is classed as "Fine tuning".
But in a nut shell ,its getting your detector to adjust its own threshold itself, so it can adjust to the ground minerals itself as we sweep ,without you having to keep adjusting it . If you Ground balance to a piece of unclean ground, your then Ground balancing to whatever's under your coil which could be a piece of Iron which will give you a false Ground balance so it HAS to be a clean piece of ground which is representing the over all ground you will need for detecting . Some detectors give you an option to use Ground Tracking but again its recommended you only use Ground tracking in CLEAN soil otherwise ,you`ll be constantly G/tracking to the trash which will render your detectors depth capabilities useless .
Now you`ve wrung my brain out at this time in the morning , I`m off for breakfast. Hope this helps your question , I`ll leave someone else to give their version of events now :thumbsup:
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DaveP
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Bors wrote: Fri Mar 12, 2021 8:30 am When detecting, the Coil is constantly ,even when we do our best to swing at the same distance across the sweep, moving at varying up and down distances. When we lower or raise our coil to/from the ground, it affects the threshold ( back ground hum)which is going on inside the electrical gubbins of the detector .
Thanks Bors but this troubles my simple 'bird' brain. If you move the coil up and down to see the range of background hum and then settle on a GB figure, I assume that must be an average result with some electronic latitude. Now, as detectors detect through a range of depths why can't the detector just be placed on the ground, or kept still above it, to work out the average. What is it about the signal (delivered or returned) that requires the up and down motion?
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shaggybfc
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I've wondered the same thing. I was told by a very knowledgeable man, (runs a detecting shop), that it you gently tap your coil on the ground and set the GB to this feedback, you won't go far wrong. I've tried this and I'm not sure if it works or not.
I've also tried finding a nice, faint single, then taking GB up and down manually,,,, without any noticeable difference between 80 - 94 .( Deus)
So..... I just keep it on 88 for all my land types....
I have no idea really, still a newbie really :)
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Bors
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DaveP wrote: Fri Mar 12, 2021 9:22 am Thanks Bors but this troubles my simple 'bird' brain. If you move the coil up and down to see the range of background hum and then settle on a GB figure, I assume that must be an average result with some electronic latitude. Now, as detectors detect through a range of depths why can't the detector just be placed on the ground, or kept still above it, to work out the average. What is it about the signal (delivered or returned) that requires the up and down motion?
As I said its Its done to measure the Negative or positivity in the ground so your detectors threshold isn`t altered when you lower or raise the coil. If you were to manually ground balance you`d see the effect more . Its when you lower the coil to the ground and if the threshold increases its telling you the present ground balance is too positive If you lower the coil to the ground and the threshold decreases as your dropping the coil its telling you the its too negative . The thing that must be achieved is to "BALANCE" this positiveness or negativity by adjustment either manually or Automatically which is what your doing when you start the Ground balance action. Your getting your detector to measure the Positivity or negativity in the Ground and adjusting your threshold to one or the other so that as you go up or down its not altering the threshold hum.Hence the detector then adjusts (in Auto) to the Grounds Electrical status and its not doing it to the Depth part of it. Depths plays no part in Ground balancing to apart(I must add) from trying by GB`ing to achieve the Max depth capable by correct GB`ing . Its only the grounds electrical /MINERAL conductivity its balancing itself to .
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DaveP wrote: Fri Mar 12, 2021 7:40 am Is there any other reason why ground balance is set by moving the coil up and down, other than to have the best chance of finding a clean piece of ground, rather than side to side?
No. :thumbsup:
The idea is to find a metal free piece of ground in all metal before GBing. You can also GB by swinging side to side, that is how tracking works. But the up & down GB technique on a known metal free patch should give a more accurate reading.
DaveP wrote: Fri Mar 12, 2021 7:40 am I only ask as my little bit of the HB is working its way through another problem.
A problem shared is a problem halved! :Thinking: :thumbsup:
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Easylife
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DaveP wrote: Fri Mar 12, 2021 9:22 am If you move the coil up and down to see the range of background hum and then settle on a GB figure, I assume that must be an average result with some electronic latitude. Now, as detectors detect through a range of depths why can't the detector just be placed on the ground, or kept still above it, to work out the average. What is it about the signal (delivered or returned) that requires the up and down motion?
Because it's a motion detector - simples! :D
A GB number is more a reflection of the type of mineralization than its intensity and is just the result of a combination of ground factors such as oxidized ferrous, moisture, salinity etc in the soil. :thumbsup:
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Roughwood
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This is an interesting thread. I have to say that I've wondered about these things myself.
Bors' explanation is very helpful (for me!) :thumbsup:
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Easylife
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If you are using the Equinox each mode or frequency can give a different ground reading as each modes Multi IQ profile is unique, so it should be ground balanced again if changed, but close enough is okay as the Nox is quite forgiving.
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DaveP
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Easylife wrote: Fri Mar 12, 2021 10:53 am is just the result of a combination of ground factors such as oxidized ferrous, moisture, salinity etc in the soil. :thumbsup:
Agree and GB measurements, as we see them, must be a summation of those to give an average as otherwise it would vary with depth.
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DaveP
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Bors wrote: Fri Mar 12, 2021 10:39 am Its only the grounds electrical conductivity its balancing itself to .
As conductivity will vary with depth the detectors must be processing an average to give us the GB.
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Bors
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DaveP wrote: Fri Mar 12, 2021 11:42 am As conductivity will vary with depth the detectors must be processing an average to give us the GB.
Ah! but your obviously forgetting Einstein's theory of evolution Chriss. . :thumbsup:
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