Joint equalization and timing recovery in a fractionally-spaced equalizer

A technique for combining equalization and symbol timing recovery is presented for use in a fractionally-spaced equalizer. This technique eliminates the need for timing recovery circuitry by sampling the received signal at a nominal rate and tracking the movement of the equalizer taps´ center of mass. Depending on whether the received signal is oversampled or undersampled, the equalizer tap weights will gradually shift toward one end of the equalizing filter. Once the center of mass has shifted one full symbol´s duration, the equalizer will shift the tap weights back to the center, along with a corresponding shift of the tapped-delay-line values, and either output two symbols (if signal is undersampled) or output an invalid symbol (if signal is oversampled). The technique allows fractionally spaced equalization and timing recovery to be performed jointly, eliminating the need for baud-synchronous sampling and reducing hardware complexity