Methods and apparatus for vibration detection

Apparatus for detecting a vibration of an object adapted for rotation, comprising:

• a plurality of magnetic field sensors for generating an RDIFF signal proportional to a magnetic field at a first location relative to the object and an LDIFF signal proportional to a magnetic field at a second location relative to the object;
• at least two rotation detectors, wherein a first one of the rotation detectors is coupled to at least one of the magnetic field sensors and is responsive to the RDIFF signal for providing a first output signal indicative of rotation of the object and wherein a second one of the rotation detectors is coupled to at least one of the magnetic field sensors and is responsive to the LDIFF signal for providing a second output signal indicative of rotation of the object;
• and
• a vibration processor responsive to the first and second output signals of the at least two rotation detectors for detecting the vibration of the object, the vibration processor comprising one or more vibration detectors including a running-mode processor coupled to the first and second ones of the rotation detectors to detect the vibration of the object in response to an unresponsive one of the first and second output signals from a respective one of the first and second ones of rotation detectors and to generate a running-mode-vibration output signal indicative of the vibration.