AC Synchro signal to digital signal converter

An AC synchro-to-digital converter for providing synchro angle values from received sensed signals representative of the actual voltage magnitudes of each of the three AC synchro stator windings and the rotor winding, comprising:

• analog-to-digital (A/D) signal interface, including differential amplifier means responsive to the actual stator winding voltage signals for providing difference stator winding signals representative of the difference voltage magnitude between a selected one of the stator windings and each of the remaining two, absolute value circuit means responsive to said difference stator winding signals for providing absolute value signals representative of each, and peak signal detection means responsive to the actual rotor winding voltage signal for providing a reference pulse signal in the presence of each of a selected polarity rotor peak voltage signal value, said A/D interface further including signal conversion means responsive to said difference stator winding signals, said absolute value signals, and said reference pulse signals, for providing in the presence of each reference pulse signal,
• a digital ratio signal representing the magnitude ratio of the smaller magnitude difference stator winding signal divided by the larger magnitude difference stator winding signal,
• digital difference magnitude signals representing each of said difference stator winding signal magnitudes, and
• digital phase signals representing the relative phase between each of said remaining stator winding sensed voltage signals and the sensed rotor voltage signal;
• and
• signal processing means, responsive to said digital ratio signal, said digital phase signals, and said digital difference magnitude signals, and including memory means for storing a plurality of identification signals associated with different subranges of synchro angle values within a total range of synchro travel, each identification signal defined as a combination of said digital difference magnitude signal and said digital phase signal value and each identifying a particular synchro angle value within its associated subrange in combination with said digital ratio signal value, said processing means providing actual synchro angle values in dependence on the value of said digital ratio signal in the presence of a particular sub-range defined by said digital difference magnitude and said digital phase signal values.