The Temporal and Spectral Characteristics of Ultrawideband Signals

Ultrawideband (UWB) technology, useful for both communication and sensing applications, uses the radio spectrum differently than the vast majority of radiocommunication technologies. UWB systems make use of narrow pulses and time-domain signal processing. Questions regarding how these systems, with their potentially very wide emission bandwidths, might affect the efficient use of the radio spectrum or cause interference to conventional radio and wireless systems must be answered before there is any large-scale deployment of UWB systems. The investigation reported here examined both the temporal and spectral characteristics of UWB signals, since all radio signals exist in both the time and frequency domains. The investigation was approached with theoretical analyses, measurement of actual UWB devices, and computer simulations. The emissions of several UWB transmitters were measured under controlled, and repeatable, laboratory conditions. Those measurement methods useful for routine measurements using commercially-available test equipment were identified. The characteristics of an aggregate of several UWB signals were examined. An initial assessment of the effects of UWB signals on several Federal Government systems was accomplished through field measurements. This report provides a basis for an assessment of the effects of UWB signals on other communication and radar systems, the study of the spectrum efficiency of UWB technologies, and the development of spectrum sharing policies and regulations.