The purpose of this book is to provide data needed to predict the interference potential of various UWB signals. The results will be useful for regulatory agencies that are currently charged with defining UWB emission limits and corresponding compliance measurement procedures. They will also be useful to the ultrawideband communications industry, which will only thrive if compliance measurement procedures fairly evaluate interference potential of all UWB signals. The approach is to inject carefully characterized interference into an operating narrowband receiver and measure susceptibility of the receiver with precisely defined signal quality metrics. Data is then analyzed to determine if there are common signal characteristics that predict interference potential. The victim receiver chosen for this interference susceptibility test is C-band satellite digital television (DTV). This receiver demodulates signals transmitted in the 3.7 to 4.2 GHz frequency range, which lies within the band allocated for UWB devices. The authors chose to generate the satellite signal in the laboratory rather than use an unpredictable live signal, to generate interference signals with a vector signal generator rather than rely solely on prototype devices, and to perform signal and system characterization measurements primarily with the vector signal analyzer to provide comprehensive data capable of being post-processed in many ways.