The popularity of Advanced Television System Committee (ATSC) mobile digital television (DTV) [mobile/handheld (M/H)] cultivates a fast growing demand on transmitter identification (TxID) in a mobile environment. The ATSC A/110 standard addresses this need with a TxID system using a radio-frequency (RF) watermark. This paper studies the use of DTV signal cancellation techniques in RF watermark detection. In particular, we develop two schemes, namely, decision feedback convolution and decision feedback equalizer (DFE) decision-directed (DD) error, to meet different application scenarios. The first scheme is designed for static and slow-fading channels, whereas the second scheme is designed for dynamic and fast-fading channels. We have conducted computer simulation on TxID over various channel conditions to evaluate the performance of our schemes. Numerical results show that DTV signal cancellation can significantly boost the signal-to-noise (SNR) level of RF watermark and thus reinforce TxID in a mobile environment.