Patent ID: 7580470

Claim:
An apparatus for recovering map information in a reception system, which recovers enhanced mode map information including multiplexing information of enhanced data and main data, the apparatus comprising: a frame synchronization recovering unit for generating a field sync signal and a field identifying signal indicating an even field or an odd field from an input data symbol by performing a frame synchronization recovery; a symbol extracting unit for extracting map symbols corresponding to an enhanced mode map transmitted by being inserted in the field sync signal from the input data symbol using an output of the frame synchronization recovering unit, the symbol extracting unit for outputting the extracted map symbols intact if the odd field is indicated, the symbol extracting unit for inverting values of the map symbols to output if the even field is indicated; a Kerdock decoder for outputting Kerdock-decoded map data and a corresponding correlation reliability value using correlation between the map symbols output from the symbol extracting unit and each Kerdock code generated in the Kerdock decoder, the Kerdock decoder comprising a symbol correlating unit for performing a process to calculate and to output a correlation value between each Kerdock code and the map symbols; a map deciding unit for identifying whether a current field is the odd field or the even field by receiving the field sync signal and the field identifying signal from the frame synchronization recovering unit and by receiving the Kerdock-decoded map data and the correlation reliability value from the Kerdock decoder, the map deciding unit for deciding map data to be used for the current field by identifying whether there is a map change if the even field is indicated; and a map interpreting unit for detecting enhanced segment information inserted in one field and a packing mode from the current map data decided by the map deciding unit, wherein the symbol correlating unit finds the correlation value between the map symbols and each Kerdock code by inverting a sign of a corresponding map symbol according to a sign of the Kerdock code and by adding the selectively inverted symbols together.