Digital VSB transmitting system and enhanced data multiplexing method in a VSB transmitting system

PURPOSE: A digital VSB(Vestigial SideBand) transmission system and an enhanced data multiplexing method are provided to be suitable for transmitting enhanced data by multiplexing a plurality of the enhanced data encoded at inter-different coding rates and transmitting the multiplexed enhanced data. CONSTITUTION: A main and enhanced data multiplexing process unit(201) multiplexes the first enhanced data encoded at an 1/M coding rate and the second enhanced data encoded at an 1/N coding rate according to a predetermined multiplexing rule by a packet unit, and converts a format of the multiplexed enhanced data into an MPEG(Moving Picture Experts Group) transport stream format. The main and enhanced data multiplexing process unit multiplexes the converted enhanced data and main data according to the predetermined multiplexing rule by a segment unit. The first encoding unit(202) successively performs the data randomize, parity addition by Reed-Solomon coding and data interleaving of a data packet outputted from the main and enhanced data multiplexing process unit. A symbol processing unit(203) converts data of a byte unit interleaved in the first encoding unit into symbols, encodes only an enhanced data symbol at an 1/L coding rate, and converts the symbols into data of the byte unit. The first decoding unit(204) deinterleaves the data of the byte unit outputted from the symbol processing unit, and removes the Reed-Solomon parity added in the first encoding unit from the deinterleaved data. A VSB transmitting unit(100) performs the trellis coding, parity addition by Reed-Solomon coding and data interleaving of the data outputted from the first decoding unit, modulates the interleaved data by a VSB transmission method, and transmits the modulated data.