Attenuation of Communication Signals on Residential and Commercial Intrabuilding Power-Distribution Circuits

The use of electric-power-distribution circuits for intrabuilding communications is ol continued and growing interest. The purpose of this paper is to present intrabuilding signal attenuation measurements taken from five different buildings. The measurements cover the range 20-240 kHz and include transmissions across power phases. The measurements complement earlier measurements by others of power-line impedance and noise. Impedance, attenuation, and noise characterize any communication channel and are needed for design of communication signaling formats, error-control codes, and communication protocols. Except over short distances, attenuation normally exceeds 20 dB, and can be much higher. The attenuation which occurs when the transmitter and receiver use different power-line phases is not always larger than when both are on the same phase. Narrow-band frequency-selective fades can occur and change as network loading changes, and can also exhibit periodic time dependence. Loading, which is time varying, greatly affects signal attenuation between network nodes. The results clearly indicate that power-line signal attenuation is highly variable and unpredictable, is variable with communication signal frequency, and is not easily modeled mathematically. The implications of our results for intrabuilding communications on power-distribution circuits are discussed.