Study of Aircraftshadowing Effects During Maneuvers for Aeronautical Telemetry

Abstract

Typical aeronautical telemetry instrumentation for a fighter aircraft comprises of multiple antennas on the aircraft, with typical placement of one antenna on the spine of the aircraft and the other on the aircraft belly. Complimentary to the aircraft instrumentation, is the fixed ground station equipped with a tracking antenna. Air to ground channel for this telemetry link is considered as line of sight propagation. But there is a link loss observed at the ground station for a certain instant of time. Possible causes of link loss/attenuation in the case are due to aircraft manoeuvring. The main objective of this paper is to study and analyze masking patterns of the aircraft instrumentation scheme. Polarization diversity combining at the RF receiver and frequency diversity combining at the tracking receiver were explored at the ground station to mitigate the effect of RF fading due to antenna masking. The RF signal levels at the ground station are analyzed with respect to different aircraft attitudes. This paper also brings out the possible causes of the RF level drop and the solutions which can be explored to overcome it.