DTV broadcast transmission is provided with a ultra wideband overlay signal which is used by suitably equipped DTV receivers to dynamically estimate the channel and allow expeditious and effective mitigation of changing multipath conditions. Periodic correlation peaks are detected in the received overlay signal, and the timing and magnitude of other peaks in the received overlay signal are used to mitigate multipath in the received signal. A DTV receiver that is not equipped to process the overlay transmission will not be significantly affected by the overlay signal.