Detection of change in the relative position of beta sensors

A method for detecting relative movement of a position of beta sensors, comprising:

• detecting a first waveform having a first period generated by a first beta sensor responsive to passage of a plurality of indicators of a beta ring past the first beta sensor;
• detecting a second waveform having a second period generated by a second beta sensor responsive to passage of the plurality of indicators of the beta ring past the second beta sensor;
• determining an offset between the first period of the first waveform and the second period of the second waveform within a controller;
• comparing the determined offset with a reference offset between the first period of the first waveform and the second period of the second waveform within the controller;
• determining if the determined offset is different from the reference offset by a first amount within the controller, wherein the first amount indicates that one of the first and second beta sensors has moved the first amount from a previous position;
• and
• generating a fault code indicating that one of the first and second beta sensors has moved at least the first amount.

A system for detecting relative movement of a position of beta sensors, comprising:

• a beta ring having a plurality of teeth thereon, wherein one of the plurality of teeth comprises an outlier tooth that is different from a remaining plurality of teeth;
• a first beta sensor for detecting movement of the plurality of teeth past the first beta sensor and generating a first output function responsive thereto;
• a second beta sensor for detecting movement of the plurality of teeth past the second beta sensor and generating a second output function responsive thereto;
• a memory for storing a reference point for a characteristic associated with the first output function and the second output function;
• a controller connected to receive the first output function and the second output function, wherein the controller is configured to:
• detect the characteristic associated with the first output function from the first beta sensor and the second output function from the second beta sensor generated responsive to passage of the outlier tooth of the beta ring past the first beta sensor and the second beta sensor;
• compare the detected characteristic with the reference point for the characteristic associated with the first output function and the second output function;
• determine if the detected characteristic is different from the reference point for the characteristic by a first amount, wherein the first amount indicates that the first or the second beta sensors have moved the first amount from a previous position;
• and
• generate a fault code indicating that the first or the second beta sensors have moved at least the first amount.