Abstract: The disclosed hunting suppressor is for use with n-phase electric motors including a stator having n windings and a rotor. The hunting suppressor is responsive to a reference clock signal characterized by a frequency f.sub.c and an associated phase angle .phi..sub.c.A controlled frequency oscillator generates n drive signals, where the drive signals are mutually shifted in phase by 180/n degrees. The drive signals are each coupled to drive a respective one of the n windings of the motor. A phase locked loop network locks the frequency and phase of one of the drive signals to that of an applied clock reference signal. With that configuration, the rotor is controlled to rotate at the frequency of the clock reference signal with substantially no hunting.

Abstract: The present invention relates to a signal processing system for generating a nulling signal for attenuating a periodic noise component from an information signal. According to one aspect of the invention, the system includes two nested feedback networks. One network detects the phase angle and frequency of the noise component, and generates a nulling signal having a phase angle and frequency substantially equal to the phase angle and frequency of the noise component. The other network detects the amplitude of the noise component, and scales the nulling signal to have an amplitude substantially equal to the amplitude of the noise component. According to a further aspect of the invention, the system includes a combining network for attenuating the noise component by combining the information signal with the nulling signal. In this way, the invention preserves the high fidelity of the information signal except over a very narrow bandwidth, adjacent to the noise signal frequency.