Analysis of low pulse-rate UWB interference into an FM receiver

As part of the DARPA NETEX (phase I) program, extensive testing and analysis were performed to determine the effect of interference from UWB transmitters on narrowband receivers. This paper describes the analysis of UWB interference into an FM receiver for the case in which the UWB pulse rate is less than the FM channel bandwidth. A closed-form expression for the baseband noise power as a function of the RF carrier-to-interference ratio (CIR) is derived. The result shows that if the desired signal is modulated, there is a sharp increase in noise power once the CIR drops below a threshold which depends on the UWB pulse rate relative to the FM receiver channel bandwidth. As explained, this analysis accounts for an effect observed during the tests