DTV transmitting system and receiving system and method of processing broadcast data

An apparatus for processing a digital broadcast signal for transmitting the digital broadcast signal, the apparatus comprising:

• a Reed-Solomon (RS) frame encoder configured to Forward Error Correction (FEC) and Cyclic Redundancy Check (CRC) encode enhanced service data to build at least one RS frame of the enhanced service data;
• a block processor configured to convert data bytes of the enhanced service data included in the at least one built RS frame into data bits, to encode each of the converted data bits of the enhanced service data at a coding rate of at least 1/2 or 1/4 to output symbols, to interleave the symbols, and to convert the interleaved symbols to output data bytes of the enhanced service data;
• a group formatting unit configured to form a data group including the output data bytes of the enhanced service data, a plurality of known data sequences and place holder bytes for main service data, MPEG headers, and RS parity data;
• a deinterleaver configured to deinterleave data in the data group;
• a packet formatter configured to remove the place holder bytes for the main service data and the RS parity data from the data group, in which the data are deinterleaved, to replace the place holder bytes for the MPEG headers in the data group, in which the data are deinterleaved, with the MPEG headers and to output enhanced service data packets;
• an interleaver configured to interleave data in the enhanced service data packets;
• and
• a trellis encoding unit configured to trellis encode the interleaved data, wherein at least one memory in the trellis encoding unit is initialized at a start of each of the plurality of known data sequences.