Abstract: The present apparatus relates to nonvolatile fault flags for use in aircraft. The term "flag" refers to an electromechanical indicator which displays a human-readable signal which identifies a fault. A fault is a malfunction occurring in the aircraft. The term "nonvolatile" refers to the feature that the signal is not lost when electrical power is terminated to the indicators. In addition, apparatus are provided for displaying the first, and only the first, fault signal received by the indicator, and for the prevention of triggering of the indicator by spurious signals.

Abstract: A synchro resolver angular position sensor provides the sine and cosine of angular position by applying a square wave excitation to the resolver stator winding. The corresponding square wave outputs of the sine and cosine windings of the resolver rotor are sampled in time synchronism with the excitation at a predetermined time phase of the square wave excitation cycle. The sampled sine and cosine amplitudes are converted into digital format via an analog-to-digital converter for application to a digital processor. The upper corners of the positively-going leading edges and the lower corners of the negatively-going leading edges of the square wave excitation waveform are rounded to minimize ringing of the sine and cosine square wave outputs from the resolver.