Investigations relative to the mitigation of interference to analog and digital radio-based avionics systems

This paper describes the preliminary investigations in to the potential of interference due to high level RF fields from high-powered broadcast, transmitters on nearby aircraft, ground-based aviation-related transmitters and on-board transmitters. The problems associated with third order intermodulation distortion, IMD, generated by high powered FM broadcast transmitters has been studied several times and has resulted in an RTCA paper on the subject. A general improvement in the dynamic range of VHF navigation and communications receivers has reduced the susceptibility to IMD of newer receivers. However, the improvement of receiver IMD performance is accompanied by an increase in potential IMD generators. The described research will, first, assess the potential sources of IMD. Second, the amount of dynamic range required to reduce the IMD levels such that the IMD will pose no threat to safety of flight will be determined. Finally, a new silicon carbide technology will be integrated into communications and navigation receivers and tested