Abstract: This paper designs an improved echo canceller for on-channel repeater in the digital terrestrial television broadcasting (DTTB) networks. The finite impulse response (FIR) filter of the conventional echo canceller is split into several sub-filters and the output error power for the different sub-filters is estimated. Based on comparison of the output error power of the different sub-filters, the improved echo canceller adaptively selects the number of sub-filters or the tap length for the echo canceller. The improved echo canceller overcomes the fault of unknown knowledge of the tap length for the echo canceller design. Simulations illustrate that the improved echo canceller can attain the lower residual echo interference compared with the conventional echo canceller.