A
Anonymous
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If we visualize an 8 X 10 sheet of paper with lines so that there are 50 horizontal lines on the page. If we put a bb or less sized target on the page it may be over a line or between two lines. The more lines there are the greater the chance that the bb will be over a line. Keep doubling the lines and the more lines the bb will be over. Consider that we want the bb to be over as many lines as we can within limits. The limit being how many lines can be drawn on the page in this example.
This illustrates a major advantage of FBS and BBS technology and one reason why frequency is important. The high frequencies have tighter line spacing so of the electromagnetic field from the TX coil so is more sensitivity to smaller targets but penetrates the soil at less depth. The low frequencies flux lines are not a tightly spaced BUT penetrate the soil deepest. So with 28 or 17 frequencies components in the electromagnetic flux we get the best OVERALL sensitivity to small targets and depth. We end up with a best depth and sensitivity at frequencies below 100khz so that is our upper limit for hobby detectors.
The more lines of flux that penetrate a target the greater are the eddy currents that are induced into the target. When eddy currents flow in the target they generate their own electromagnetic field. That electromagnetic field stores enegry just as there is enrgy in the filed from the TX coil. Energy can be moved from one point to another using an electromagnetic filed. What we want to do is move the coil in such so that the maximum number of lines of force strike a metal target. The hot strip down the center of the coil is where the flux lines are the tightest so maximum inductance of eddy current flow in the target occur.
There are lines of flux or force around the detection coil. The further from the hot strip you are the less lines of force strike a target. A large metal target has more conductance than a smaller one. The conductivity of the two targets is the same no matter what the size of the metal as long as they are the same metal. The targets on the edges of the detection flux can warp the detection field. We want a large footprint to cover enough ground so that we don
This illustrates a major advantage of FBS and BBS technology and one reason why frequency is important. The high frequencies have tighter line spacing so of the electromagnetic field from the TX coil so is more sensitivity to smaller targets but penetrates the soil at less depth. The low frequencies flux lines are not a tightly spaced BUT penetrate the soil deepest. So with 28 or 17 frequencies components in the electromagnetic flux we get the best OVERALL sensitivity to small targets and depth. We end up with a best depth and sensitivity at frequencies below 100khz so that is our upper limit for hobby detectors.
The more lines of flux that penetrate a target the greater are the eddy currents that are induced into the target. When eddy currents flow in the target they generate their own electromagnetic field. That electromagnetic field stores enegry just as there is enrgy in the filed from the TX coil. Energy can be moved from one point to another using an electromagnetic filed. What we want to do is move the coil in such so that the maximum number of lines of force strike a metal target. The hot strip down the center of the coil is where the flux lines are the tightest so maximum inductance of eddy current flow in the target occur.
There are lines of flux or force around the detection coil. The further from the hot strip you are the less lines of force strike a target. A large metal target has more conductance than a smaller one. The conductivity of the two targets is the same no matter what the size of the metal as long as they are the same metal. The targets on the edges of the detection flux can warp the detection field. We want a large footprint to cover enough ground so that we don