Frequency distance separation between land mobile radio systems

This paper introduces a methodology to determine the frequency and distance separation relationships for similar and dissimilar land mobile radio systems. The methodology proposed is demonstrated by two case studies which involve a 25 kHz system and a 12.5 kHz system. The methodology presented separates the interference problem into the spectral, spatial and time aspects. The ISI model is essential in determining the spectral interactions and off-channel rejection factor between two dissimilar systems. The propagation and interference models are used to determine the distance separation required to bring the interference levels down to acceptable limits. The time factors represented by the activity factors of the systems determine the probability of interference between systems. The same methodology can be applied to consider interference between other types of dissimilar radio systems.