Audio frequency ripple (AFR) control
The audio frequency ripple control method is the oldest existing method of data transmission on supply lines and may also be termed powerline technology. The function is very easy. One or several AFR amplifiers superimpose an alternating voltage onto the supply voltage. The AFR receivers evaluate the control voltage and use it to switch the relays and thus the lighting. [more]EFR
The function of the European radio ripple control (EFR) is similar to that of the audio frequency ripple control method. With this kind of control system, data is not transmitted through the electricity network but by means of long-wave radio.By definition, long waves are waves in the frequency range 30 to 300 kHz. In the installation, the EFR receivers are located either in the sub-distribution or in each lighting point. [more]