FREQUENCY OFFSET COMPENSATION USING DOTTING SEQUENCES

摘要

The along and perpendicular rails of a received signal (e.g., modulated usin g multi-phase shift keying) are rotated to compensate for frequency offsets be tween the carrier frequency of the received signal and the reference frequency of the local os cillator. The rotation angles are updated, based on the rotated along rail, during dotting sequence s in the received signal. In one implementation, the dotting sequences are detected based on t he rotate perpendicular rail. The beginnings of dotting sequences are detected by thre sholding the average on the perpendicular rail and the ends of dotting sequences are detected by analyzing the encoded data for non-dotting-sequence values. In a cordless phone application, diffe rent dotting sequences may be used to distinguish base-to-handset transmissions from hand set-to-base transmissions.