Power line communication system

摘要

A system for communicating digital information over wires having a great deal of harmonic distortion, such as a power line, employs a transmitter which transmitter which creates a carrier wave for each of a plurality of signals to be sent. This carrier wave has frequency lobes positioned between the frequency lobes of the harmonic distortion. Each of the lobes of a single carrier signal is encoded with the same bit value during a given bit period. This signal is then mixed with any existing signal on the wire. At a remote receiver coupled to the wires, the signal is sensed, filtered, and Fourier transformed into coefficients. The signal-to-noise (S/N) ratio of each Fourier coefficient is determined by a novel S/N estimation technique. The coefficients are weighted based upon the S/N ratio estimation, and decoded, preferably by an inner product of the weighted Fourier coefficients. Additionally, the S/N ratio estimates could be time averaged before being used in the weighting and bit decoding.