A digital television (DTV) receiving system includes a tuner, a demodulator, a known data detector, an equalizer, a transmission detector, and a block decoder. The tuner receives a DTV signal having a data frame in which main and mobile service data are multiplexed. The demodulator demodulates the DTV signal, and the known data detector detects known data included in the mobile service data. The equalizer equalizes the demodulated DTV signal using the detected known data, and the transmission parameter detector detects an error correction mode from the equalized DTV signal. Finally, the block decoder decodes the equalized DTV signal for error correction using the detected error correction mode.