Method and transmitter for encoding data

A method of encoding data as a sequence of symbol elements for transmission over a channel at a symbol rate, each individual symbol consisting of at least two symbol elements that are to be transmitted in consecutive time slots as defined by said symbol rate, the method comprising: - obtaining a value representative of a bandwidth of said channel; - selecting a set of coefficients such that a spectral extent of said symbols is substantially contained within said bandwidth of said channel; - generating said symbol elements by multiplying symbols of said data by said set of coefficients, each coefficient determining the level of a respective symbol element of one of said symbols for a different one of said consecutive time slots; and - transmitting said symbol elements over said channel.