Digital AM broadcasting (DAMB) channels are investigated in detail. First, the normalised ICI power of time-variant DAMB channels is calculated to determine the range of total subcarriers of an OFDM-based DAMB system. The number of subcarriers provides a base for the subsequent channel estimation. Then, two time-frequency channel estimators with real coefficients are constructed and analysed for a DAMB system based on OFDM. Finally, their BER performance is simulated in DAMB channels. In conclusion, the 1-D estimator provides a better trade-off between BER performance and computational complexity than a 2-D estimator. The low complexity of a 1-D estimator makes it suitable for use in wireless communication systems such as WLAN, DVB and so on.