The IEC 61334 standard is an international standard for powerline transmissions at low data rates with Spread Frequency Shift Keying( S-FSK). The method has a high reliability and is suitable for smartmeters, water meters and the computer system SCADA, Supervisory Control and Data Acquisition, for collecting and analyzing real-time data.
The specifications described in IEC standard 61334 deal with the equipment and characteristics of the power lines, which are handled in the physical layer: the media access method and the management interface. S-FSK ke ying is used on the robust physical layer, on which the IP protocol is based: IP over S-FSK. The physical layer transmits small data packets with tones between 20 kHz and 100 kHz during the zero crossing of the network voltage. If a tone is transmitted, this corresponds to a digital 1, in the other case it is a digital 0. According to the standard, 1, 2, 4 or 8 bits can be transmitted during the zero crossing. In three- phase power lines, separate signals are transmitted on each phase line, which increases the data rate.
The low data rate specified in the standard is limited by the transmission during zero crossing.