Patent ID: 7401008

Claim:
A method of determining at least one instantaneous phase angle estimate at a selected time from a proper rotation signal, including the steps of: (a) inputting the proper rotation signal to a processor; (b) extracting an amplitude-normalized half wave of the proper rotation signal wherein the extracted amplitude-normalized half wave includes start and end times and a local extremum having well-defined phase angles, the extracted amplitude-normalized half wave having a value at the selected time; and (c) determining the at least one instantaneous phase angle estimate of the extracted amplitude-normalized half wave at the selected time by obtaining a data point from a linear interpolation spanning the start and end times and the local extremum, the abscissa of the data point being equal to the value of the amplitude-normalized half wave at the selected time and the at least one instantaneous phase angle estimate being provided by the ordinate of the data point.