Due to the inductive nature of synchros and resolvers there will be some inherent phase shift between the stator output and rotor excitation. Referring to the operations manual specifications for the 8810A or multifunction cards, under the heading "Phase Correction" or "Immediate Module Specifications", the 8810A or S/D module will correct for and operate with up to +/- 60 degrees of phase shift between the reference (excitation) source and stator output. Phase Lock Loss Status is monitored and reported to the user. The module converters employ a technique which synthesizes a perfect internal reference signal from the stator (or SIN, COS) inputs thereby reducing the phase shift to essentially 0 degrees. There is no standard for RDC’s and phase shift. There is no military standard for resolver specifications. There is a standard for Synchros (Arinc 407-1). However, most technically-modern RDC’s now typically incorporate the design technique of utilizing a synthesized ref. circuit to correct the phase shift.