Patent ID: 7764937

Claim:
A frequency error system for measuring a sign and magnitude of a carrier frequency error in a received complex signal, comprising: a first detector operating to detect at least one quadrant transition of the received complex signal in a first rotation direction; a first accumulator that accumulates a number of first rotation direction quadrant transitions detected by the first detector during a time period; a second detector operating to detect at least one corresponding quadrant transition of the received complex signal in a second, opposite, rotation direction; a second accumulator that accumulates a number of second, opposite, rotation direction quadrant transitions detected by the second detector during the same time period; and a subtractor that subtracts from the accumulated first rotation direction quadrant transitions the second, opposite, rotation direction quadrant transitions to obtain a difference value, a sign of that difference value being indicative of the carrier frequency error sign and a magnitude of that difference value being indicative of the carrier frequency error magnitude.