An apparatus for transmitting a broadcast signal, the apparatus comprising: an external encoder (301-1) for external coding of signaling data; an external encoder (301) for external coding of service data; an internal encoder (303-1) for internal coding of the external encoded signaling data by means of an LDPC coding scheme; an internal encoder (303) for internal coding of the external encoded service data by means of an LDPC coding scheme; a first interleaver (304-1) for interleaving bits of the internal encoded signaling data; a second interleaver (304) for interleaving bits of the internal encoded service data; a demultiplexer (305-1) for demultiplexing bits in interlaced signaling data; a demulitiplexer (305) for demultiplexing bits in the interlaced service data; a first symbol mapper (306-1) for mapping constellation bits of signaling data in preamble symbols; a second symbol mapper (306) for mapping in constellation the demultiplexed bits in the service data interlaced in service data symbols; a header inserter (307) for inserting a header at the front of the service data symbols and constructing at least one segment of data based on the header and the service data symbols; a third interleaver (308-1) for interlacing data in the preamble symbols; a fourth interleaver (308) for interlacing the at least one segment of data; a frame constructor (103) for constructing a signal frame based on the data interleaved in the preamble symbols and the at least one interleaved data segment; a modulator (104) to modulate the signal frame by an Orthogonal Frequency Division Multiplexing method, OFDM; and a transmitter (105) for transmitting the modulated signal frame, wherein the preamble symbols are divided in the frequency direction into layer 1 blocks, L1, of the same bandwidth and bandwidth of each block L1 corresponds to a total number of active subcarriers assigned to a single channel, the L1 blocks are repeated in the frequency domain with a repetition rate that is the bandwidth of the L1 block.