METHOD AND APPARATUS FOR AUTOMATIC FREQUENCY CORRECTION ACQUISITION

摘要

An improved automatic frequency correction acquisition system utilizes an automatic frequency correction (AFC) loop (22) having an acquisition mode and a tracking mode. The AFC is switchable in response to predetermined control signals between the acquisition mode and the tracking mode. A carrier to impairment ratio estimator (26) is coupled with the automatic frequency correction loop (22) for estimating the carrier to impairment ratio of the incoming carrier signal. An automatic frequency correction controller (30) is coupled with the automatic frequency correction loop (22) and with the carrier to impairment ratio estimator (26) and is responsive to the carrier to impairment ratio estimate being at or above a preselected threshold value for producing a tracking control signal (24) comprising one of the predetermined control signals. The automatic frequency correction loop (22) is responsive to the tracking control signal (24) for switching from the acquisition mode to the tracking mode.