Date Added: Dec 2011
The actual idea of a telephony structure shows a Private Automatic Branch EXchange (PABX) directly controlling a whole communication system. Ringing and caller identification signals, voltage setting for the phone sets among other important parameters all are transmitted using twisted pair cables that have to be installed and distributed along the building. The use of existing indoor power lines as the communication channel benefits the installation of the telephony system because the network infrastructure is already mounted. However, power lines behave noisy and aggressive when transmitting high frequency signals and in order to establish effective communication, modern modulation and transmissions schemes have to be implemented. With this new conception, the transmission scenario changes completely and so does the system.