Degradation of Base Station Radio Reception at UHF and VHF:Due to the Effects of Automobile Ignition Systems and Multipath Propagation,

摘要

The report contains the findings in the second of a two-part study on the degradation of VHF and UHF land mobile radio reception. Observations for this study on base station reception were made at 37.5MHz, 88MHz, 153MHz, 459MHz and 956MHz. The study concludes that when a land mobile base station antenna is approximately 50feet high and located 300feet or less from a heavily traveled road,ignition radiation was the main cause of interference at 37.5and 88MHz. At 459and 956MHz,multipath interference predominated. As the base station antenna was moved away from traffic,degradation due to ignition interference decreased while multipath interference was unaffected. The degradation of reception in the land mobile radio services from the ignition systems of motor vehicles and the additional adverse effect of super-noisy vehicles suggests that either the present voluntary SAE J551(a) radiation standard is inadequate or a considerable number of motor vehicles do not comply with the standard.