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

电力线通信(PLC)通过电力线传输信息数据，电力线通常用于提供电能。如果分配频率扩展到短波频段(2-30 MHz)，高速电力线载波通信是可能的，但在短波频段有许多无线电通信系统，如船载无线电和航空无线电，因此有必要减少电力线泄漏电场而不影响无线电通信系统。因此，在本研究中，为了定量地阐明电磁波从电力线中泄漏的机理，我们尝试从一个简单的电力线模型出发，利用矩量法计算电力线的泄漏电场。由于计算值与实测值吻合较好，证实了矩量法计算模型对计算电力线泄漏电场是有效的。其次，通过PLC调制解调器测量了不同形式的电力线正弦传输特性对正交频分复用信号传输特性的影响。将实际环境中各种形式的输电线路分为两个基本元件，即插座式支路和开关式支路。测量与PLC调制解调器连接的每个基本元件的PHY速率(物理速率)。在计算机上组成了发送和接收系统，并对物理层速率进行了仿真。通过与实测值和计算值的比较，发现在电力线传输特性具有宽带和高电平衰减的情况下，PLC调制解调器的PHY速率受影响最大，而在具有窄带群时延变化的情况下，对PLC调制解调器的PHY速率影响不大。

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.