This part of GB/T 31983 specifies low voltage narrowband power line communication (PLC) physical layer protocol specifications based on Orthogonal Frequency Division Multiplexing (OFDM) technology, including physical layer protocol data unit format (PPDU), channel coding, interleaving, OFDM. Modulation, physical layer signal frame generation and continuous transmission mode and power frequency synchronization zero-crossing time slot transmission mode. This section applies to data transmission and communication in the 3 kHz to 500 kHz band through indoor or outdoor low voltage AC distribution lines or DC transmission lines. Based on the physical layer protocol specification in this part, a complete PLC system composed of multiple communication nodes established on the low-voltage power distribution network also includes a data link layer (DLL, which is controlled by the medium access control sub-layer MAC and logical link). Control sub-layer LLC composition), and the application layer related to the specific application scenario. Typical low-voltage narrow-band power line communication applications include intelligent meter reading (AMR), AMI/AMM, home intelligence control, street lighting control, intelligent building, four-set copying, and other applications of Smart Grid, such as: Electric vehicle charging control, etc. This section is also applicable to medium voltage power line communications, as well as long-distance power line communications in urban and rural areas.