An apparatus for receiving data from Orthogonal Frequency Divisional Multiplexed (OFDM) symbols transmitted by a transmitter, the OFDM symbols comprising a plurality of data bearing sub-carriers and one or more continuous pilot sub-carrier symbols, which are located in the same position for each of the OFDM symbols and scattered pilot carrier symbols, which change position between one OFDM symbol and another in accordance with a predetermined pattern, the predetermined pattern of scattered pilot carrier symbols being in accordance with a Digital Video Broadcast-Terrestrial, DVB-T, standard and the data bearing sub-carriers carrying data symbols which are paired by generating a first pair of modulation symbols for each of the pairs of data symbols, the first pair of modulation symbols forming first and second modulation symbols of an Alamouti cell, forming a first version of the OFDM symbols by modulating the sub-carriers allocated for carrying the one or more pilot carriers in accordance with the predetermined pattern, and modulating the sub-carriers allocated for carrying the data with the first and second data symbols of the Alamouti cell, generating a second pair of modulation symbols for each of the pairs of data symbols, the second pair of modulation symbols forming third and fourth modulation symbols of the Alamouti cell formed for the pair of data symbols in the first version of the OFDM symbols, forming a second version of the OFDM symbols by modulating the sub-carriers allocated for carrying the one or more pilot carriers in accordance with the predetermined pattern, and modulating the sub-carriers allocated for carrying the data with the third and fourth modulation symbols of the Alamouti cell, the first version of the OFDM symbols being transmitted from a first antenna, and the second version of the OFDM symbols being transmitted from a second antenna, the apparatus comprising a receiver (200, 204, 206, 208, 210) for receiving the first version of the OFDM symbols transmitted from the first antenna, and the second version of the OFDM symbols transmitted from the second antenna, a demodulator operable to form an estimate of a first pair of modulation symbols for each of the pairs of data symbols from the first version of the OFDM symbols, using the one or more pilot carriers, the first pair of modulation symbols forming first and second modulation symbols of an Alamouti cell, to form an estimate of a second pair of modulation symbols for each of the pairs of data symbols from the second version of the OFDM symbol, using the one or more pilot carriers, the second pair of modulation symbols forming third and fourth modulation symbols of the Alamouti cell corresponding to the pair of data symbols in the first version of the OFDM symbols, a data detector operable to generate an estimate of each of the pairs of the data symbols from the first, second, third and fourth modulation symbols corresponding to each of the Alamouti cells recovered from the first and second versions of the OFDM symbols, wherein for at least one of the pairs of data symbols carried by the first and second versions of the OFDM symbols, the sub-carriers carrying the modulation symbols of the first and second modulation symbols and the third and the fourth modulation symbols forming the Alamouti cells are separated within the first and second versions of the OFDM symbol respectively by at least one other data bearing sub-carrier or one or more of the pilot carriers, and the apparatus including a controller operable to provide the predetermined pattern of scattered and continuous pilot sub-carriers for the OFDM symbols to the data detector and to control the data detector to detect the pairs of data symbols according to whether the pairs of first and second and third and fourth modulation symbols are separated by the one or more other data bearing sub-carriers or one or more of the scattered or continuous pilot sub-carriers according to the provided predetermined pattern of scattered and continuous pilot sub-carriers for the OFDM symbols, and the data detector is operable to detect the pairs of data symbols carried by the sub-carriers by adapting a detection technique for recovering the data symbols from the Alamouti cells depending on whether the pairs of data symbols are detected from sub-carriers which are adjacent or whether the sub-carriers have one or more other sub-carriers or pilot carriers inter-posed there between, and if detecting a pair of the data symbols from pairs of data symbols, which are separated by the at least one other data bearing sub-carrier or pilot carrier, using a different estimate of a coefficient of the channel frequency response corresponding to the position of each of the sub-carriers within each of the first and second versions of the OFDM symbol, or if the first and the second modulation symbols and the third and the fourth modulation symbols are carried by adjacent sub-carriers, detecting the pair of data symbols carried by the sub-carriers by assuming that a coefficient of the channel frequency response corresponding to the position of each of the sub-carriers within each of the first and second versions of the OFDM symbol are the same.