Importance

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Abstract

A power line communication (PLC) apparatus wherein a carrier is derived to avoid determinable interference harmonics. In order to transmit data on a power line containing the television interference or other determinable interference harmonics, the present invention uses redundant carriers at a frequency between the television interference harmonics. In the preferred embodiment, the first carrier is positioned at 118 KHz and the redundant carrier is positioned at 133.7 KHz for the PLC apparatus designed for use in the United States. Other carrier frequencies are used for other countries in order to avoid interference harmonics at a slightly different frequency. The present invention includes a waveshaping and modulation circuit for generating the modulated data waveform for output over the power line. In the preferred embodiment, the waveshaping and modulation circuit includes a waveshape ROM for storing samples that represent the appearance of the carrier waveshape. Once the appropriate waveshape is selected from the waveshape ROM, the 256 discrete points of the waveshape are clocked out an interface line to a DAC, a filter, an amplifier and on to a PLC coupling network for isolating and coupling the signal onto the power line. On the receive side, receive filters are used to separate the received data from determinable interference harmonics. These filters comprise four matched filters, two for each channel. These filters operate in cooperation with the waveshaping and modulation circuitry in order to capture the signals modulated between determinable interference harmonics such as television interference harmonics.

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First Claim