Modem for communication over power lines wiring

(Used in organizing sensor networks, home and industrial automation)

Designed modem uses power line wiring to transmit digital data between data collection devices, actuators, and control and interface devices to a PC. Scheme modem and its construction is designed to minimize its size, the number of discrete components used and simplify its assembly. Using the electrical wiring allows to link the parts of the electronic system without the use of additional radio and laying of communication cables. There is a possibility of hidden data, redundant communication channels, providing communication in remote places.

This modem uses Narrowband Powerline Communication technology (NPLC) and the type of modulation Frequency Shift Keying (FSK). The center frequency is 132 kHz. Signals corresponding to the bit “0” and “1” are orthogonal and their carrier frequency differ by only 4 kHz, which can greatly simplify the input filter circuit.

To reduce the BER (Bit Error Rate) indicator in equipping the premises of these modems, analyzes the spectrum of the interference of all possible consumers of electricity in the power supply used. According to the analysis of the information signal repeaters are installed, which reduces the effect of noise on the quality of narrowband transmitted signal. With the same purpose the transmission protocol CAN (Controlled Access Network), adapted to NPLC technology – serial communication protocol that supports real-time distribution control.