Method and apparatus for eliminating direct current offset

An apparatus for eliminating direct current offset, comprising:

• an Euclidean distance calculating module, configured to calculate Euclidean distances between every two demodulation symbols of a plurality of demodulation symbols based on Quadrature Phase Shift Keying modulation;
• a first determining module, configured to determine four sets from the plurality of demodulation symbols in accordance with the Euclidean distances between the demodulation symbols, each set corresponding to a modulation direction for the QPSK modulation;
• a rough estimating module, configured to perform Euclidean distance weighted summation on the determined four sets respectively, and select a demodulation symbol with the minimum weighted summation value from each set as a rough estimation point for the QPSK modulation, so as to obtain four rough estimation points;
• a second determining module, configured to re-determine four sets from the plurality of demodulation symbols in accordance with the Euclidean distances between the demodulation symbols and the rough estimation points;
• a precise estimating module, configured to perform Euclidean distance weighted summation on the re-determined four sets respectively, and select a demodulation symbol with the minimum weighted summation value from each set as a precise estimation point, so as to obtain four precise estimation points;
• and
• a direct current offset eliminating module, configured to perform direct current offset calculation and compensation in accordance with the precise estimation points.