Multi Coil Quadrature Demodulation Signal Chains for Proximity Measurement
Multi coil quadrature demodulation isolates amplitude and phase in inductive proximity chains, resolving sub-micron targets while rejecting thermal noise.
Coil Mutual Inductance
Magnetic Coupling Parameter
Inductive interaction between two separate electrical conductors quantifies the voltage induced in one circuit by a changing current in another. Coil mutual inductance determines the efficiency of energy transfer in non contact sensing systems. The physical geometry of the windings and the permeability of the medium between them dictate the strength of this link.
It scales with the number of turns in both the primary and secondary elements.
Spatial Alignment
Proximity and orientation of the coils govern the magnitude of the coupling coefficient. When the axes of two coils are perpendicular, coil mutual inductance drops toward zero. This characteristic allows designers to create null balance sensors where a target object disrupts the symmetry.
Precision in the winding process is necessary to minimize parasitic effects.
Permeability Factor
Ferrous materials or high conductivity metals near the coils alter the magnetic flux path. This modification changes the measured coil mutual inductance and provides the basis for eddy current displacement sensors. External interference from motors or power cables can inject noise into the secondary winding.
Shielding or differential wiring helps maintain signal integrity.
Measurement Verification
Measurement of this parameter occurs at a specific reference frequency where parasitic capacitance is negligible. Lab standards provide a known value against which field instruments are compared during production. If the coils shift due to thermal expansion, the resulting change in spacing alters the coupling and introduces a measurement error that persists until recalibration occurs.
Verification at multiple orientations ensures the alignment tolerances are met.