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

A digital television (DTV) transmitting system for processing digital broadcast data, the DTV transmitting system comprising:

• a Reed-Solomon (RS) frame encoder for generating a RS frame by adding RS parity data to bottom ends of columns of a RS frame payload and adding Cyclic Redundancy Check (CRC) checksum data to right ends of rows of the RS frame payload having the RS parity data, the RS frame payload including enhanced data;
• a block processor for encoding a first portion of data in the RS frame with a first coding rate and encoding a second portion of data in the RS frame with a second coding rate;
• a group formatter for mapping the encoded first portion of data into a first region of at least one data group, mapping the encoded second portion of data into a second region of the at least one data group, and adding known data sequences, signaling information, RS parity data place holders and MPEG header data place holders to the at least one data group;
• a packet formatter for removing the RS parity data place holders from the at least one data group and replacing the MPEG header data place holders of the at least one data group with MPEG header data, thereby outputting enhanced data packets;
• a trellis encoder for trellis encoding data in the enhanced data packets;
• and
• a transmitting unit for modulating the trellis-encoded data and transmitting the modulated data.