There is provided a scheme for centering data prior to detection. It is characterized by: determining carrier frequency error, and pre-adjusting (G1) the data detection process to compensate for that error throughout the ensuing data detection. This scheme for reliable multi-level data detection is further characterized by: upon detection of carrier presence, determining carrier frequency error, gating (G1) a voltage associated with the frequency error (C1) to the differential amplification process (DIFF) to establish common mode rejection and compensating for that error (C1) throughout the ensuing multi-level data detection, and then analog-to-digital conversion (A/D) of the differentially amplified multi-level data. A scheme for computationally centering the subsequent data detected to compensate for the error is also provided.