Power Line Intercom - narrowband voice communication over power line

Designing a PABX system using the existing power line infrastructure as the transmission medium is an effective method of implementing a fast and easily installable communication solution. The scope of this research is to develop such a system for a small scale organizational environment to avoid the complexities and time consumption of cable installation. As the power line transmission technique, we used narrowband frequency shift keying to counter the noise disturbances in power line. In addition we used a novel communication protocol to further reduce the effects of noise and to achieve reliable transmission. We integrated the switching function into the central unit which is the central control element in the system. We were able to achieve voice communication at the rate of 2kbps and to switch between four extensions. Further improvements in the voice quality can be achieved by using advanced noise reduction algorithms.