Rotary Variable Differential Transformers (RVDTs) are devices that function by
the motion of the rotor within the electro-magnetic field of the stator. This
produces an electrical output signal, which has a known relationship to the
mechanical motion. In simple terms the RVDT measures angular or rotary motion.
These devices are available in an AC to AC configuration, giving an AC output
signal at the same frequency as the input signal but with amplitude proportional
to the rotor angular position.
RVDTs have a limited linear range covering any range up to ± 70° max.