Detection of transient signals in multipath environments

This research examines methods for detecting unknown transient waveforms that are contaminated by noise. The sensitivity of the performance levels of the energy detector and the lack of knowledge about the structure of the transient waveform motivate the examination of other moment- or spectra-based detection techniques. We examine the performance of a bispectral energy detector and show that its performance will degrade if the bispectra is smoothed and that signals with no bispectral content can be detected if the bispectra is not smoothed. Further, it is shown that the performance levels of the bispectral detector are slightly better, and slightly less sensitive, than those of the energy detector for the multipath linear frequency modulated signal. Finally, the performance levels of narrowband implementations of the energy and bispectral energy detectors are compared. It is shown that for a large enough sample, the performance levels of the bispectral detector are nearly as good as those of the optimal energy detector for the single narrowband signal case. However, when the received waveform contains multiple narrowband components, the narrowband bispectral detector performs slightly better than the energy detector. >