Method for detecting engine rotation direction

A system for determining a direction of rotation of a rotatable shaft, comprising:

• a disk rotatable in synchronization with the rotatable shaft having a plurality of contiguous zones, the zones including a set of first zones and at least one second zone, each of the first zones having first and second areas;
• a sensor disposed adjacent the disk for generating a sensor signal in response to the passing of the zones as the disk rotates, the sensor signal generated during the passing of the first zone being different than the sensor signal generated during the passing of the at least one second zone;
• and
• a controller coupled to the sensor, the controller being configured to:
• receive the sensor signal from the sensor,
• determine periods between the passing of the first areas of the first zones based on the sensor signal,
• detect the at least one second zone based on the sensor signal, and
• determine the direction of rotation based on the periods determined after the detection of the at least one second zone.

A method for determining a direction of rotation of an engine, comprising:

• rotating a disk in synchronization with a shaft of the engine, the disk having a plurality of contiguous zones of approximately equal angular extent, the zones including a set of first zones and at least one second zone, each of the first zones having first and second areas, the first zones being different than the at least one second zone;
• generating a sensor signal using a sensor disposed adjacent the disk in response to the passing of the zones as the disk rotates;
• determining periods between the passing of the first areas of the first zones based on the sensor signal;
• and
• determining the direction of rotation based on the determined periods.