a dtv transmitter includes a pre - processor pre - processing enhanced data , a data formatter generating enhanced data packets including known data , a multiplexer multiplexing the enhanced data packets with main data packets , a data randomizer randomizing the multiplexed data packets , an rs encoder rs - encoding the randomized data packets , and a data interleaver interleaving the rs - coded data packets , where a plurality of known data sequences are included in the interleaved enhanced data packets . finally , the dtv transmitter further includes an enhanced encoder which codes each block of enhanced data placed between any two of the known data sequences and bypasses the interleaved main data packets .