DATA COMMUNICATION OVER POWER LINES

摘要

A power line communication system (20) includes a field-programmable gate array (FPGA) having a sine wave approximator (28) driven by a high frequency clock. The sine wave approximator (28) generates a high frequency sine wave-shaped communication signal on command by a processor (22). The data transmission scheme includes sending a sequence of fixed length and fixed frequency cells wherein each transmitted cell is of one of four phases 0, 90, 180 or 270 degrees relative to the phase of a preceding transmitted cell with the first transmitted cell designated as a zero phase reference cell. Data transmissions are synchronized by the voltage zero crossings of the AC power line (32) and each transmission consists of 27 cells evenly distributed over the AC voltage line half cycle. The high frequency sine wave shaped communication signal is superimposed on the low frequency (60Hz) AC power line (32) via a transconductance amplifier (30) which draws current from the AC power line (32) via a full wave bridge rectifier (34).