Patent ID: 8443412

Claim:
A method of transmitting a broadcast signal in a transmitter, the method comprising: pre-processing, by a preprocessor, first service data comprising audio or video data for a mobile service, the first service data capable of being transmitted via a same channel as second service data comprising audio or video data for a main service, wherein pre-processing the first service data comprises: randomizing the first service data, generating a Reed-Solomon (RS) frame through which an RS frame payload including the randomized first service data is RS—Cyclic Redundancy Check (RS-CRC) encoded, wherein the RS frame is separated into a plurality of portions, wherein a size of the RS frame payload is 187 by N bytes, and wherein N is an integer corresponding to a length of each row of the RS frame payload, forming data groups of the first service data, wherein each data group includes signaling information, a plurality of known data sequences that have pre-determined values, one of the plurality of portions, second service data place holders, RS parity data place holders, and MPEG header data place holders, and wherein the signaling information includes information indicating a number of the data groups to be transmitted during a transmission frame, and removing the second service data place holders and the RS parity data place holders and replacing the MPEG header data place holders with MPEG header data to output first service data packets; multiplexing, by a multiplexer, the first service data packets and second service data packets, wherein the second service data packets include the second service data; randomizing, by a randomizer, the multiplexed second service data packets and the MPEG header data in the multiplexed first service data packets; and transmitting, by a transmission unit, a broadcast signal that includes: the first service data packets including the randomized MPEG header data, and the randomized second service data packets, wherein a parade of the formed data groups is transmitted during slots in the broadcast signal, the slots being basic time periods for multiplexing the first service data and the second service data.