Patent ID: 6157292
Filing Date: 2000-12-05
Classification: H04B

Abstract:
A data communication system for transmitting an outbound communication signal over an AC power grid having a low frequency power signal, said system comprisinga signal input device located at an upstream point on said power grid;a signal receiving device located on said power grid at a point downstream of said input device;said signal input device including a signal input connection for receiving an input signal, a spread spectrum arrangement for coding the input signal into a low frequency band to produce a spread spectrum coded input signal, and an arrangement for injecting the spread spectrum coded input signal onto the low frequency power signal of said power grid to produce a coded power line signal,said signal receiving device being connected to said power grid and receiving said coded powerline signal, said signal receiving device processing said coded powerline signal to substantially remove the harmonics of said power signal, by using a high pass filter to initially filter the signal and remove the first, third and fifth harmonics of the power signal and remove the signal below about 400 Hz and subsequently digitizing the remaining signal and processing the digitized signal using digital harmonic rejection techniques to further remove the effects of the harmonics of the power signal, despreading the remaining signal to extract the input signal, and wherein said low frequency band is in a frequency range readily transmitted through any capacitor banks and transformers of said power grid between said input and said receiving device.