A transmitter transmitting payload data using OFDM symbols includes a frame builder configured to receive the payload data, receive signalling data for use in detecting and recovering the payload data at a receiver, and form the payload data with the signalling data into transmission frames. A modulator is configured to modulate a first OFDM symbol with the signalling data forming a part of each of the frames and to modulate one or more second OFDM symbols with the payload data to form each of the frames. The transmitter combines a signature sequence with the first OFDM symbol, so that the first OFDM symbol can be detected within the frame before the second OFDM symbol. The transmitter includes a pilot signal inserter configured to insert a number of pilot symbols on selected sub-carriers of the first OFDM symbol sufficient to estimate a coarse frequency offset of the transmitted OFDM symbol.