Keywords

aeronautical telemetry, multipath

Abstract

This work was supported by the Science & Technology Test & Evaluation Spectrum Efficient Technologies Program sponsored by the US Air Force under contract F04611-02-C-0020. Channel sounding data collected from an airborne transmitter over the Pacific Ocean off the coast of Pt. Mugu, Naval Air Station, was analyzed and used to model multipath propagation over the ocean. The experiments showed that at 8.000 GHz, over the water multipath propagation is well modeled by a three-ray propagation model. The first ray (or propagation path) is the line-of-sight propagation path. The second ray is a strong specular reflection determined by the geometry defined by the airborne transmitter, the ground-based receiver, and the sea surface. For the flight profiles used, the delay of this path was between 10 and 50 ns. The third ray is a more diffuse, random reflection whose amplitude is significantly smaller than the amplitude of the specular reflection and whose mean excess delay is 57 ns with an RMS delay spread of 20 ns. Relative to the ground-based multipath environment, the sea-based multipath environment changes much more rapidly.