MULTI-LEVEL SYMBOL SYNCHRONIZER

摘要

A symbol synchronizer for a communication receiver receiving four level (NRZ) data signals includes a reference clock generator for generating a referen ce clock signal having a predetermined time period, a state change detector for detecting state changes occurring within the received four level (NRZ) data sign als over the predetermined time period to enable selecting a time location value corresponding to the detected state change and a magnitude detector, for generat ing magnitude values representing the magnitude of the received four level (NRZ) dat a signals over the predetermined time period, an accumulator for accumulating a total time location/magnitude value for the time location/magnitude values selected, and a phase adjusting circuit which is responsive to the total time location/magnitude value for adjusting the phase of the reference clock signal relative to the received four level (NRZ) data signal.