AccurateCalls
Senior Member
Just remember high iron sites. The iron/nails not all on top of ground or near surface necessarily and can be in different levels (planes).
Also actual separation abilities need to be taken into account.
See this link post 3.
When Eqx 11” coil is talked about and the 6” coil.
The percentage advantage far less than one might think with the significant coil size differences.
http://www.dankowskidetectors.com/discussions/read.php?2,152652,184093#msg-184093And
It's trivial to extend the 2D Probability Theory based argument into 3D. E.g. if a larger circle has a greater probability of encompassing multiple objects on a plane, so does a larger 3D EM field being projected into the ground.
It should be noted in 2D the area of the circle increases by the square of the radius (greater area = greater probability of encompassing multiple targets), while in 3D the volume of the electromagnetic field increases by the cube of the radius (greater volume = greater probability of encompassing multiple targets). So the probability based argument is actually stronger in 3D
Just keep in mind signal processing definitely matters, and these are approximations based on some theoretical "perfect" metal detector (one that process signals with 100% accuracy / no EMI, etc.) . It's still possible to make a bad enough metal detector with sufficiently crappy signal processing such that it defies this relationship.
Also, in the link, NASA Tom clearly is implying that Minelab has actual numerical data suggesting the 6" inch coil separates better compared to the 11". So even they have proven Calabash wrong in his assertion that smaller coilers do not separate better than larger ones.
Besides, 11% improvement is huge! As he states, given a random target configuration, the 6" coil will unmask an extra 11 coins per 100 trials. That's a huge advantage (also shows they are taking a probability based approach as well in the internal analysis!).
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