Dear support:
we are designing a metal detector using the LDC1612。In the laboratory environment, the sensor can respond to metal targets. However, in actual working conditions, there may be water or other conductive objects near the metal, which may cause the metal signal to be annihilated.
We already know that fsensor decreases when there are other conductors in the target range; When metal is detected, fsensor increases; Ideally, metals can be distinguished, but when there is a change in the non-metallic conductor of the environment near the metal, the metal signal may be annihilated. For example, in environment 1, when there is no metal target, fsensor is 100, and when metal is detected, fsensor is 120; However, in environment 2, when there is no metal target, fsensor is 80, and when metal is detected, fsensor is 100. In this case, I can't tell what 100 means.
We have found an answer in the forum,FAQ(e2e.ti.com/.../faq-inductive-sensing-faq---frequently-asked-questions)Q22，This answer describes a phenomenon that when the hand touches the coil, the tank capacitance will increase, resulting in an error in the inductance calculation.
In Chinese Forum(e2echina.ti.com/.../658971
) also describes the reason for this effect, that is, LDC only measures the resonant frequency fsensor after LC interaction, which is the common result of L and C. Because LDC sensor only measures the frequency, it does not know who caused the frequency change.
So my understanding is that the reason for this phenomenon is that the environment changes the tank capacitance of the sensor. Is there a solution to this situation? How to correct the capacitance?
Thank you for your answers!
