On Performance of Digital Radio Receiver in Non-Gaussian Interference

Licentiatavhandling, 2003

Interference from electrical equipment can degrade a co-located digital radio receiver severely. To avoid this performance degradation it is necessary to have estimation methods to predict the influence from an interference environment on a radio receiver in advance. To protect radio services, electrical equipment must fulfill international standards regarding maximum allowed levels of radiated electromagnetic energy. Unfortunately, present emission requirements are not developed to protect digital radio receivers. Furthermore, present requirements are only defined for the frequency range below 1 GHz, why there is a need for new emission requirements suitable to protect digital radio services. In this work, the influence from electrical equipment on digital radio receivers is considered. Since interference generated from electrical equipment often has a non-Gaussian character, the commonly used Gaussian approximation is not always applicable for performance analysis. For this issue, a practical method to estimate the performance degradation is necessary. The amplitude probability distribution (APD) has earlier been shown to be an applicable measure of an interference signal in order to be correlated to its impact on a digital radio receiver. In this thesis, the usage of this measure in conventional error expressions is clarified. It is also shown that this relationship between the measured APD of an interference source and the maximum degradation of the receiver can be deployed for emission requirements. The direct use of the measured APD of an interference source for the performance estimation of the radio system requires that the bandwidths of the measuring and the radio receiver under investigation are approximately the same. When this is not the case a solution for how to convert the APD measured by one bandwidth to be valid for a bandwidth according to the receiver under investigation. The conversion of the APD to another bandwidth is developed for a certain type of noise.