Study on technologies decreasing leaked electromagnetic wave from a power line communication with high bit rate

PLC（电力线通信）通过使用通常用于供应电能的电力线来传输信息数据。如果分配频率扩展到HF频带（2-30 MHz），则高速PLC是可能的，但是在HF频带中存在许多无线电通信系统，例如船舶和航空无线电，那么必须通过减少电力线泄漏的电场来不影响无线电通信系统。因此，为了定量地阐明电磁波从电力线泄漏的机理，本文尝试从电力线的简单模型出发，利用矩量法计算泄漏电场。计算值与实测值一致，证明了利用矩量法建立的计算模型在计算电力线泄漏电场时是有效的。接下来，通过PLC调制解调器测量了各种形式的电力线的正弦传输特性对OFDM（Orthogonal Frequency Division Multiplexing）信号传输特性的影响。在真实的环境中具有各种形式的电力传输线被分类为两个基本元件，即出口型分支和开关型分支。针对与PLC调制解调器连接的每个基本元件测量PHY速率（物理速率）。在计算机上搭建了OFDM发送和接收系统，并对PHY速率进行了仿真。通过与实测值和计算值的比较，揭示了电力线调制解调器的PHY速率在具有宽带和高电平衰减的电力线传输特性的情况下受影响最大，而在具有窄带群时延变化的情况下不受影响。

PLC (power line communication) transmits information data by using a power line, which is usually used to supply electric energy. If assignment frequency expands to HF band (2-30 MHz), PLC with high speed is possible, but there are many radio communication systems such as ship and aerial radio in HF band, and then it is necessary not to affect the radio communication system by decreasing leaked electric field from power line. Therefore, in this study, in order to clear quantitatively mechanism that electromagnetic wave is leaked from the power line, we try to calculate the leaked electric field from a simple model of power line by using method of moment. Since calculated values agreed with measured one, it was confirmed that the calculation model using the method of moment was effective to calculate leaked electric field in the power line.Next, we measured what influence the sinusoidal transmission characteristics of the electric power line with various forms gave to the transmission characteristic of OFDM (Orthogonal Frequency Division Multiplexing) signal through PLC modem. The electric power transmission line with various forms in a real environment is classified into two basic elements, which are an outlet type branch and a switch type branch. PHY rate (Physical rate) is measured for each basic element connected with the PLC modem. OFDM sending and receiving systems are composed on the computer, and the PHY rate is simulated. By comparing with measured and calculated values, it is revealed that PHY rate of PLC modem is most affected in the case of the power line transmission characteristics having broad band and high level attenuation and is not affected in the case of that having narrow band group delay variation.