A permanent magnet motor controller injects a periodic signal into a field oriented controller of the brushless motor. Phase currents in stator windings of the brushless motor are measured. A d-axis current and a q-axis current are determined with a transform of the phase currents. The d-axis current and the q-axis current are demodulated to extract an angle dependent current signature that includes a sine component of a rotor angle estimate and a cosine component of the rotor angle estimate. The rotor angle estimate is determined by processing the sine component and cosine component.