In this paper an assessment concerning the potential impact of interference caused by transmissions of wireless avionics intra-communication systems onto aeronautical radio altimeter operating co-frequency is presented. The radio altimeter model utilized for the assessment accounts for realistic scattering and antenna characteristics to describe echo signals returned by the Earth surface. It includes a detailed description of the signal processing and detection stages allowing for a comprehensive analysis of the interference impact.
The interference of wireless avionics intra-communication transmissions is modeled by offset quadrature phase-shift keying modulated signals which are added to radio altimeter receive antenna output signal. The assessment covers a broad range of potential interference scenarios. It includes a detailed analysis of the spectral characteristics of wireless avionics intra-communication signals observed in the radio altimeter detection stage and an evaluation of their impact onto the altitude detection reliability.
