Patent ID: 7164733

Claim:
A method, embodied in a program of instructions executable by a machine, for compensating digital data demodulation phase uncertainty, the method comprising the steps of: identifying a phase reference quadrant, the phase reference quadrant comprising a phase reference axis; receiving known digital data; receiving an analog signal; down-converting the analog signal by demodulating an in-phase (I) signal and a quadrature (Q) signal to provide I_received data and Q_received data, respectively; forming a phase vector from the known digital data, determining which quadrant the phase vector is located in and rotating the phase vector to the phase reference quadrant if it is determined that the phase vector is not located in the phase reference quadrant such that: if the phase vector is determined to be in quadrant II, set I_data to substantially equal Q_received data and set Q_data to substantially equal −1*I_received data; or if the phase vector is determined to be in quadrant III, set I_data to substantially equal −1*I_received data and set Q_data to substantially equal −1*Q_received data; or if the phase vector is determined to be in quadrant IV, set I_data to substantially equal −1*Q_received data and set Q_data to substantially equal I_received data; rotating the phase vector 45° by setting an I_rotated data substantially equal to I_data+Q_data, and setting a Q_rotated data substantially equal to Q_data−I_data; measuring the resulting angle between the rotated phase vector and the phase reference axis; and generating a phase error signal proportional to the resulting angle.