Various aspects of the instant disclosure are directed towards communicating symbols over a power line carrying alternating current, based upon frequency variations in the alternating current. In accordance with some embodiments, a line driver couples data-carrying symbols over the power line, via a waveform. Variations in the alternating current are monitored and used for accessing a lookup table that stores data entries that define data useful for providing steps of the waveform. The accessed data entries are used to drive a line driver with stepped data, and therein modulating alternating current on the power line with the data-carrying symbols at a frequency that is tied to the frequency of the alternating current.