Ground/Sensitivity Probe deciphering

[bigjer]

Happy Leap Year!!!

Thanks to the great replies in this forum....I think I am almost understanding what my V3i is telling me....(Almost) lol

On the subject of ground probe and sensitivity probe.....to fine tune the machine to the soil you are over...

My usual ground probe readings are ; Phase VDI -90 to -93
level of Mineralization readings are 1 - 3 %

My usual sensitivity probe reading are Signal% 18 - 23 %
Noise is 1-4%

Stock D2 coil

NOW......

Here is what I "think" all this means.......jump in and correct me where I am wrong..ok?

Ground probe is tell me my mineralization is low....so I can use a low ground filter ...as long as my swing speed is slowwwwwwwwwww.
Sensitivity probe ...I interpret to be telling me that I am losing 18-20% of my signal to the ground, which is ok...i think.....and can I can adjust my sensitivity settings to keep this below 20% or so.....correct?

Noise reading tells me I do not have much EMI or other outside interference...so I don't have to worry about changing my filter or offsetting the frequency's.


I have read many postings and watched many vids on this subject, but still have not found ONE explanation EXACTLY how to interpret and apply the date gained by these probes.

Thanks for bearing with me....

 

[Rob (IL)]

Happy Leap Year!!!

Thanks to the great replies in this forum....I think I am almost understanding what my V3i is telling me....(Almost) lol

On the subject of ground probe and sensitivity probe.....to fine tune the machine to the soil you are over...

My usual ground probe readings are ; Phase VDI
level of Mineralization readings are 1 - 3 %

My usual sensitivity probe reading are Signal% 18 - 23 %
Noise is 1-4%

Stock D2 coil

NOW......

Here is what I "think" all this means.......jump in and correct me where I am wrong..ok?

Ground probe is tell me my mineralization is low....so I can use a low ground filter ...as long as my swing speed is slowwwwwwwwwww. Pretty normal reading for ground. It is mostly iron instead of salt.Most ground that we see is 178 (-94) to 165 degrees except salt which falls close to 90 degrees (VDI 0). Nonferrous targets (coins and such).VDI 0 - +95

Sensitivity probe ...I interpret to be telling me that I am losing 18-20% of my signal to the ground, which is ok...i think.....and can I can adjust my sensitivity settings to keep this below 20% or so.....correct? You aren't losing signal. You are losing the ability to handle a larger signal before the detector overloads. You are doing well and can go higher than 20% as longer as your detector doesn't overload on shallow targets when hunting.

Noise reading tells me I do not have much EMI or other outside interference...so I don't have to worry about changing my filter or offsetting the frequency's. (correct)


I have read many postings and watched many vids on this subject, but still have not found ONE explanation EXACTLY how to interpret and apply the date gained by these probes. I think you are doing fine. If you have ground coming in at -94(VDI) with a signal strength of 2% and another ground coming in at -91 with a signal strength of 7%, it would seem to me that the ground coming in at -91 is more mineralized even though it is a less negative VDI. A signal strength of the ground as follows 0 to 10% weak, 10% to 20% Moderate and 20% and up to be strong. Try to keep it at 20% or less. The lower the mineralization, the slower one should sweep - which may mean a lower filter should be selected. The phase tells you composition (between purely ferrous and purely salt), while the signal strength tells you the concentration (more mineralized).

Thanks for bearing with me....

 

[bigjer]

Thanks Rob.....think I have it now.

 

[MHirschmann]

So....I have read, re-read and re-re-read this thread and I still don't understand how to use "Ground Probe" under ground tracking and "Probe" under sensitivity. I have been reading everything I can find about figuring out these functions and my ADHD brain doesn't seem to want to understand it. Is there a "write-up for dummies" on this topic out there? I can't seem to figure out what the probe signal percentage and noise percentage mean, nor can I figure out how the ground probe phase and strength play into everything. I know that these features can help me in some way but until I figure out exactly how to use them, they will remain useless to me. I would greatly appreciate if someone could help me with this. I know its probably a dumb question but I have not found a write-up that explains how to use these features in a way that my ADHD brain chooses to understand.

Thank you very much -Marc

 

[Rob (IL)]

First in this post I will explain the sensitivity probe which is the easier.

The signal percent is telling you is how close you are getting to the detector overloading on a target. The lower the percent the bigger the target signal the detector can process without overloading. At around 60% the detector pretty much overloads. Even up to the low 40% range the detector will handle most signals except the shallow BIG targets. In the 20% range it can handle 99% of all signals.

In reality run the RX as high as you want as long as the detector remains stable. This is the same for all detectors not just the V. This signal percent setting does not affect performance unless you run the RX so high it is unstable or it causes overload. It's like a temperature gage in a car. It lets you know how close you are to getting into trouble.

----------------------------------------------------------------------------------------------
The noise% measures the External Interference. 0% or a low number indicates very little external noise and low ground interference, thus allowing for using a higher preamp RX Gain. A signal strength of the ground as follows 0 to 10% weak, 10% to 20% Moderate and 20% and up to be strong. A high % reading of Noise of 50% or more would require you to:

If your noise is EMI, you can try; 1) Freq Offset, 2) Decrease RXG, 3) Salt Mode, 4) 22.5Khz Single frequency, 5) Filter change, 6) Smaller coil.

If your noise is Ground noise you can try; 1) Filter change, 2) Decrease RXG, 3) Salt Soil 4) Salt Mode, 5) Increase BCR, 6) Smaller coil.

IT IS JUST ANOTHER TOOL. Many guys don't even use it and do fine.

 

[Rob (IL)]

Now lets try the ground probe. Everything the V3 sees gets a VDI number. The the ground then will also have a vdi number. So the VDI number at the top is just the VDI of the ground.

[attachment 224925 2012-02-29_215133.jpg]
In this chart reverse the 0 and 180 for the below explanation. It makes no difference it's just how Whites does it.

In this chart you see where the ground VDI numbers fit. The shaded area shows normal soil. Closer to -95 more ferrite closer to 0 salt.

Once you zero the machine and lower it to the ground your phase angles should come in between 0 and +180 (as with anything there will be exceptions - ground conditions, noise, what have you). A ferrite bead will come in very close to 180 degrees (-95 VDI) which is close to where most normal ground comes in and pure conductors will come in around 0 degrees (+95 VDI). Salt water (wet beach or fields with lots of fertilizer and wet) comes in close to 90 degrees (0 VDI) Approximate numbers. So it is just telling you where your soil type fits on the chart.

The signal strength in % at each frequency currently in use is displayed.

 

[MHirschmann]

Rob, you are a legend. Your response should be put in some kind of V3i for dummies section because it finally makes sense. Having ADHD, it might have been your included image that finally "clicked" with me but I get it now. Thank you so much. I say that I understand it now but we will see when I take the V out for a hunt. A lot of the time something seems to make sense and then I get out there and forget everything that I had learned. Hopefully your info will make as much sense when I get out as it seems right now. Thank you again for your help and happy hunting -Marc

 

[R-Chi]

Greetings: Would some one know if ice or frozen ground would throw these calibrations off? Living in Green Bay is not fun this time of year reading post from others being able to dig.
Thanks, R-Chi

 

[bigjer]

Yes.....It throws off the "shrinkage factor" lol
Seriously......I don't think frozen ground reads any differently than thawed dirt. Its just the retrieval that is harder. read it in Ground probe if you have any doubts.

 

[pulltabMiner]

Two questions:

When we speak of non-normalized VDI's, are we speaking of the Raw phase readings in that chart above?

And if my ground is reading -88, is my ground tracking/ground balance going to automatically "reject" this VDI? Would I gain anything but manually rejecting this VDI?

Thanks!

 

[Larry (IL)]

No, Raw Phase and VDI Scale are two different readings. Normalized VDI makes the VDI number the same on all three frequencies IE: a quarter is 83. If you turned normalization off, each frequency would have a different VDI's for the quarter.

Yes, that is the purpose of ground balancing, to reject the ground so that it is not considered a target. You can manually reject the ground portion of the VDI scale as many of us do, but I really don't know if there are any advantages to doing it.

 

[yazoo]

Seems like some where back in the V3i history on here Andreak said it had no bearing on the ground rejection one way or the other by rejecting. Yazoo

 

[Gary mi]

this is good stuff...

 

[Rob (IL)]

You are right but Magic still likes to do it. If you reject it yourself there may be no gain but there is no harm.

 

[magic]

Great posting Rob! You the man!

 

[dene97]

Is it easier to simply bypass trying decipher the probe and goto pinpoint mode while cycling through the ground filters to find the least "chatty" signal? I'm probably missing the point completely here. Lol

 

[whackidoodle]

Rob, what exactly does the machine do when you "zero" the ground probe? I see my signal strength drop to 0% and the phase numbers roll back to the negative ranges. Then the V.D.I. and phase angle jump around, often one positive/the other negative and then vice versa, back and forth until they both gradually climb to the positve again. Is this just the same mathematical function that the machine performs when you ground balance normally using the trigger/enter method?

 

[Rob (IL)]

It will remove the system / coil offsets and enable the user to achieve a more accurate reading of the ground.