Methods, apparatus and computer programs for transmitting and/or receiving information are described. Information encoded in a carrier signal comprising a modulation pattern superimposed on a grid frequency at which electricity flows in a synchronous area of an electric power grid, is decoded by measuring, at a receiving device, a characteristic relating to a frequency of electricity flowing in the electric power grid, accessing data indicative of one or more predetermined code patterns and performing a correlation process to determine a correlation between the modulation pattern and one of the one or more predetermined code patterns. The information is decoded on the basis of the determined correlation. This enables information to be easily transmitted within a synchronous area of the electric power grid.