For high-speed distribution power network communications, it is necessary and important to study the characterizations of power network channel such as power network noise level, channel attenuation and impedance matching. Power network noise exists in the whole available frequency range and cannot be eliminated. Channel attenuation is related to data transmission distance and multi-path reflection, which is caused by discontinuous position in the power network and impedance mismatch between the modem and low voltage power network. To study the characterization of network input impedance will improve the impedance matching and decrease power attenuation of data transmission. It has measured low voltage power network impedance in common residential area over the frequency range of 5k~ 20kHz in reference [1]. This frequency range is applied to low speed carrier communications. Measurement of the power network input impedance characterization has carried out in industrial environment over 100Hz~10MHz, in order to investigate the channel characterization in higher frequency[2]. To study the feasibility of constructing a small LAN with low voltage power network, Japanese researcher analyzed the low voltage power network impedance characterization [3].
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