A method for data transmission includes forming a notched radio-frequency (RF) burst according to one or more data values, where a bandwidth of the notched RF burst is at least two percent of the center frequency of the notched RF burst. Forming a notched RF pulse includes altering, according to the data, at least one of the amplitude and phase of one or more selected components, where each of the selected components has a bandwidth within the bandwidth of the notched RF burst.