Interference in Communications and Navigation Avionics from Commercial FM Stations.

摘要

The effects of commercial frequency modulation (FM broadcast stations on communications and navigation avionics were investigated employing several classes of avionics receivers. Flight tests were completed employing site frequencies with intermodulation interference determined by a computer program culling for possible intermodulation products in selected midwestern and southern states. Laboratory measurements were accomplished on the receivers and antenna pattern measurements of typical aircraft antennas were obtained to determine the areas that improvements can best be applied to alleviate the FM interference problem. Results indicate that a 10 dB increase in rejection of FM signals in avionic receivers would eliminate most FM interferences. Included is a proposed method utilizing the Venn diagram approach for predicting possible FM interference assignments under consideration. It is recommended that a flight test program be established to determine FM spectrum signatures and power levels at airports. (Author)