Abstract: A synchronous signal generator is provided for use in conjunction with an aircraft engine having a spool and an engine output shaft driven by the spool. The synchronous signal generator includes a generator housing, a generator output member rotatably mounted in the generator housing, a once-per-revolution timing mark on the generator output member, and conversion gearing disposed within the housing and configured to couple the engine output shaft to the generator output member. The conversion gearing rotates the generator output member at substantially the same rotational frequency as the spool when the conversion gearing is coupled to the engine output shaft.