Considered an analog device, and has digital counterparts such as the digital resolver, rotary (or pulse) encoder.
A resolver is a type of rotary electrical transformer used for measuring degrees of rotation. It is considered an analog device, and has digital counterparts such as the digital resolver, rotary (or pulse) encoder.
Similar to encoders, resolvers are also electromechanical devices that convert mechanical motion into an electronic signal. However, unlike an encoder, a resolver transmits an analog signal rather than digital. It is essentially a rotary transformer with one primary winding and two secondary windings that are phased 90 mechanical degrees as shown in Figure 2. The resolver output requires control inputs and logic that can interpret analog signals.
Resolvers lend themselves to maximum duty applications because of their simple component similarity to electric motors (windings, laminations, bearings, and carrier). The lack of optics and precision alignment increases shock and vibration capabilities. The lack of both optics and solid state electronics allows for use in high radiation environments. Resolvers have been time tested and proven, but the analog output limits the options that are available.