Power line communication impedance profiling and matching for broadband applications.

Power line communication(PLC) is a wired communication technology that has recently received a lot of attention due to its attractive prospects towards home and /or neighborhood network applications as well as smart grid technologies. It allows establishing digital communications without any additional wiring requirements. Effectively, one’s home and/or neighborhood wiring contributes into a smart grid to deploy various data services. It is well known that the power grid is one of the most pervasive infrastructure built to provide electricity to customers, therefore, utilizing this infrastructure for digital communications will only result in an ubiquitous telecommunications network. It is common practice to use wires to establish a physical connection in many telecommunications channels, but most electronic devices already have a pair of wires connected to the power lines. Therefore, these wires can be used to simultaneously establish digital communications. Thus, power line communications can be used as an alternative solution to more established technologies such as wireless, coaxial and optical communications. As a promising technology, PLC has attracted a lot of research and has become an active area of research which continues to evolve over time. Notwithstanding its advantages, PLC has issues, namely, severe noise at low frequencies and varying characteristic impedance. This is primarily because the power line channel was not originally designed to be used for communications, thus, it remains a harsh channel. Other challenges arise from the fact that there are different wiring practices around the world, unpredictable loading characteristics as well as differentialand common-mode characteristic impedance. As a result, there is a considerable amount of noise signal attenuation during data transmission. Loss of signal can be addressed by increasing the power at the transmitter, noise reduction and/or reducing channel attenuation to improve the signal-to-noise ratio. However, PLC modems are subject to legislation that impose a limit with regards to the signal levels in the lines. Power lines are good radiators at high frequencies which makes them behave like large antennas with the ability to intercept other radiations in the same frequency range. The radiated signal is proportional to the currents in the line, thus, increasing line currents will not solve the problem but would rather lead to violation of electromagnetic compatibility (EMC) regulations. In this work, an alternative solution is provided which seeks to address the issue of signal attenuation caused by the changing input impedance of a typical power line channel. The deleterious effects of noise are not considered since this work focuses on broadband PLC in the 1–30 MHz frequency range. The objective of this work was to design and build an impedance adaptive coupler to mitigate effects of channel attenuation caused by varying impedance. In this way, the propagating signal will “see” a uniform impedance and as a result the data output will be improved. The work was facilitated by measuring several impedance profiles of PLC channels in the band of interest. Typically, the network topology of PLC networks is not known and the building architectural blueprints are