e vsb enhanced encoder 113 selects the training sequence t instead of the known data place holder and then outputs it thereto therefore the known data can be outputted without additional encoding on the other hand the byte bit converter 631 of the u c encoding unit 630 converts the enhanced data byte to enhanced data bits and then outputs them to the 1 2 encoder 632 the 1 2 encoder 632 encodes inputted one bit to two bits to output them thereto the 1 2 encoder 632 is implemented with a convolution encoder or a low density parity check ldpc encoder etc which can use block codes also the 1 2 encoder 632 may selectively adopt a block interleaver 633 according to implementation objectives for example assuming that one byte of the enhanced data is extended to two bytes as null bits are inserted among bits thereof in the e vsb pre processor 101 the byte bit converter 631 removes the null bits of inputted bytes and then outputs only effective data bits to the 1 2 encoder 632 the 1 2 encoder 632 encodes one bit input to two bits on the basis of block coding and the block interleaver 633 inputs the two bits to perform block interleaving therefor the block interleaving is related to the total system performance and may be used in any interleavings such as a random interleaving here the 1 2 encoder 632 performs encodings based on block units the block size must be determined such that the block interleaver 633 can perform block interleaving according to the present invention the block size can be determined by input format of.