Driving Signal
Alternating current waveforms applied above one megahertz generate rapidly varying electromagnetic fields in transducer coils. Implementing high-frequency excitation improves the response time of inductive displacement sensors. This method provides the energy needed to induce measurable currents in nearby conductive targets.
Eddy Generation
Rapidly changing magnetic fields induce circular current patterns on the surface of conductive materials. The strength of these currents depends on both the frequency of the excitation and the conductivity of the target. These induced currents create an opposing magnetic field that alters the coil impedance.
Skin Mitigation
Electromagnetic field penetration is restricted to a thin layer near the surface of the target at elevated frequencies. This limitation concentrates the eddy currents within a shallow depth, which minimizes the influence of subsurface material variations. The skin depth is calculated using the conductivity and permeability of the target along with the excitation frequency.
Designing the sensor for high-frequency operation ensures that the measurement remains sensitive to surface-level changes.
Noise Rejection
Frequency-selective filters isolate the sensor response from low-frequency electromagnetic interference and power grid noise. This isolation increases the signal-to-noise ratio in industrial environments. Using bandpass filters centered on the excitation frequency ensures reliable measurement data.
