Statistical Characterization of Medium Wave Spatial Variability Due to Urban Factors

The recently developed digital radio systems for the medium wave (MW) band require accurate field strength prediction methods for coverage calculi. Traditional prediction methods do not consider the influence of urban factors on MW ground-wave propagation. This influence causes signal strength time and spatial variability which in turn, provoke drop-outs below reception threshold values. In this letter the ground-wave spatial variability is statistically analyzed in urban environments by means of empirical data from four extensive field trials. The experiments were carried out in different urban environments and at different frequencies of the MW band. Prior to the analysis, long-term and short-term components of the signal were separated by means of the generalized Lee method (GLM). The results show the attenuation caused by different urban factors. These attenuation values should be added to the signal strength predicted median values in order to ensure correct reception.