DTV receiving system and method of processing DTV signal

A receiving system, comprising:

• a signal receiving unit for receiving a broadcast signal including a data group, the data group comprising mobile service data, a first known data sequence, and a plurality of second known data sequences, wherein the first known data sequence has a first M-symbol sequence and a second M-symbol sequence wherein the first M-symbol sequence and the second M-symbol sequence have a first pattern, wherein each of the plurality of second known data sequences has a second pattern other than the first pattern, wherein the plurality of second known data sequences are spaced 16 segments apart within the data group, and wherein the second pattern is positioned from a last symbol to a previous N symbol in each of the plurality of second known data sequences;
• a known data detector for detecting position information of the first known data sequence and the plurality of second known data sequences from the data group included in the broadcast signal and performing initial frequency offset estimation using the first known data sequence;
• an estimator for estimating channel impulse responses (CIRs) based on the detected position information of the plurality of second known data sequences;
• and
• a distortion compensator for compensating for channel distortion of the mobile service data using the estimated CIRs.