A link quality indicator for analog FM transmission systems

This work describes a method to determine the link quality of analog frequency modulated (FM) transmission systems (especially wireless microphones) with the help of digital signal processing. We exploit the amplitude variations of a disturbed FM transmission to estimate the signal to interference plus noise ratio (SINR) of the received signal. Furthermore, the statistical measure kurtosis is used to determine the type of interference. After the theoretic description and derivation of the algorithms, the approach is confirmed with simulations. Finally, measurements and results of a hardware implementation show the applicability of the presented link quality estimator for instance in cognitive wireless microphone systems.