bkravitz_spectrav3
New member
I was wondering how to interpret the phase and strength settings in the ground menu.
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how do i interpret the strength and phase settings in ground menu
- Thread starter bkravitz_spectrav3
- Start date
"PHASE ANGLE" is the measured difference between the transmitted signal and the signal received from the target. Different materials have different characteristics (resistivity, reflectivity, conductivity, density, etc) which affect the signal that is returned from that specific target. It is this difference between the transmitted and returned signal (phase angle) that is measured by.
The detector only reports VDIs converted from positive phase angles (0 to 180 degrees). The negative angles aren't valid assuming that the machine is calibrated correctly. In the ground probe screen, you may see negative angles if you are holding the coil in the air so there is no real signal coming in - just noise, or you haven't zeroed it first. Once you zero the machine and lower it to the ground, or read your target, 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.
Ground should fall between 0 and 180 degrees. In air, when you zero the detector, you will see phases of both positive and negative values - those are just noise and don't pay attention to them. If you are getting a negative phase for any of the frequencies when you lower the loop to the ground however, you probably have an overload problem. 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
The VDI reading is converted from the ground phase normalized to standard VDI units. It's either going to be from the strongest signal if the detector is running best data, or the average of the two strongest signals if correlate is selected. 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. 0-10%=low mineralization, 11-25%=moderate and 25% on up = high/very high. 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).
To get the phase of your target, put the coil on the ground away from the target and press the zero button - that captures the ground for separating its effects from the target. Then put your coil over the target. That should get you pretty close to the phase of the target. The VDI number at the top is the normalized reading. The numbers for each of the 3 frequencies are the phases that each frequency sees for the target. In the ground probe, the phase angles are not normalized, just the VDI. It was intended to be used to just check out the phase of the ground, but, it can also be used this way to check out a target if desired.
By determining the ground
The detector only reports VDIs converted from positive phase angles (0 to 180 degrees). The negative angles aren't valid assuming that the machine is calibrated correctly. In the ground probe screen, you may see negative angles if you are holding the coil in the air so there is no real signal coming in - just noise, or you haven't zeroed it first. Once you zero the machine and lower it to the ground, or read your target, 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.
Ground should fall between 0 and 180 degrees. In air, when you zero the detector, you will see phases of both positive and negative values - those are just noise and don't pay attention to them. If you are getting a negative phase for any of the frequencies when you lower the loop to the ground however, you probably have an overload problem. 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
The VDI reading is converted from the ground phase normalized to standard VDI units. It's either going to be from the strongest signal if the detector is running best data, or the average of the two strongest signals if correlate is selected. 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. 0-10%=low mineralization, 11-25%=moderate and 25% on up = high/very high. 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).
To get the phase of your target, put the coil on the ground away from the target and press the zero button - that captures the ground for separating its effects from the target. Then put your coil over the target. That should get you pretty close to the phase of the target. The VDI number at the top is the normalized reading. The numbers for each of the 3 frequencies are the phases that each frequency sees for the target. In the ground probe, the phase angles are not normalized, just the VDI. It was intended to be used to just check out the phase of the ground, but, it can also be used this way to check out a target if desired.
By determining the ground
earthmansurfer
Active member
Nice info Rob.
New user and I've been wondering the same thing. A little more information taken from the White's forum:
New user and I've been wondering the same thing. A little more information taken from the White's forum:
deolslyfox said:
deolslyfox said:
ROBearthmansurfer
Active member
Yeah, he said it was fine, but his whole quote makes it sound a bit more forgiving, even condoning to share (note the end). Generally speaking, quoting others while giving the website, usually benefits traffic and is accepted on the internet (though larger corporations, in particular - newspapers, are a bit stricter). But quoting out of context is another story of course. Anyway, I know not to make this forum a link to other forums.
deolslyfox said:Tell Rob I said its "OK this time" ....No problem .... Folks "lurk" on various forums all the time .... Information sharing, especially if it helps someone in the hobby is ALWAYS a good thing ....
"None of us is as smart as all of us ...."