Bipolar pulsing, target retentivity, coercivity, a pathway to PI discrimination?

[dbanner]

Well, here is the very basic idea.
A positive going pulse, current increase along x axis, target reaches saturation. Current decays to zero, however target magnetization does not return to it's starting point( let's call it zero, neglecting the earth field) but to a point which we call retentivity.

On the negative cycle, the current increases, but in opposite direction, saturating the target, now in the opposite direction, however this point of maximum saturation (optimal magnetivity) is not the inverse of the positive going saturation point.

That's because the starting point of magnetization for the negative going cycle is the previous point of retentivity after the positive going current returns to zero.

My assertion is that because both saturation points are not symmetrical, different metals will have different degrees of asymmetrical saturation points distinctive enough to be measured by dsp.

[dbanner]

What I'm getting at here is that the Target's reflected impedence response is not symmetrical for both halves of the excitation current, and more than that, it value varies with frequency.

[dbanner]

If this could be measured, might this be a basis for discrimination????

Discrimination based on magnetivity rather than conductivity.

[Carl-NC]

Simple test... use a bipolar TX (CT coil is the easiest) and pulse the (-) side, quickly followed by the (+) side, followed by the RX sample. Disable/enable the (-) pulse and see if iron gives different results.



My guess is you might see a slight difference when the target is close to the coil, but otherwise not.

[dbanner]

I was thinking to sample between the pulses. So positive pulse, sample, store then negative pulse, followed by sample. Subtract from first sample. Repeating multiple times while sweeping through a predetermined range of pulses of shortening intervals.

The process would be complex, sort of like interrogating the Target's magnetivity, based on this concept of retentivity and coercivity.

This process would be a subroutine, which would only be initiated by the operator once a target is discovered by "normal" detection method. Sort of like in pinpoint mode where the search head is stationary over the target, doing it's interrogation routine.

[dbanner]

Furthermore, the pulse intervals could be frequency modulated at rates related to the phase of metals.

And no, I'm not trolling. Just throwing out ideas to kick the ball further down the field.

[Elliot]

Some further ideas: This approach may help determine the likely size of the target. Once the target size is estimated, you could measure the Tau of the RX signal (minus the Tau of the coil) and map out the likely type of metal being detected.

[dbanner]

Precisely!!!