Analysis of Long-Range VHF Radio Waves Propagation to Specify Protection Ratios Between Coexisting DRM+, RAVIS and IBOC Systems

The potential problem of mutual interference between different digital sound broadcasting systems such as DRM+, RAVIS and IBOC (HD-Radio) in the Band II of VHF range is being considered. Propagation prediction methods for point-to-area communication paths for terrestrial VHF services are analyzed. The criteria for the selection of transmitters - potential sources of interference have been determined. Their limiting distance is determined based on the attenuation (basic transmission loss) in free space. The basic conditions of the EMC for the scenario of interference between different broadcasting networks have been determined. The field strength of the wanted signal shall be calculated for 50% locations and 50% reception time. The field strength of the interfering signal shall be calculated for 50% locations and 1% reception time taking into account the combined location correction factor. It is shown that the combined location correction factor is 15.6 dB for outdoor reception and 18.1 dB for indoor reception (for 95% of locations) for closed paths and 10.7 dB on open paths.