A GNSS code multipath model for semi-urban, aircraft, and ship environments

The University of Colorado Advanced GNSS Multipath Model integrates 3D structure models, electromagnetic ray-tracing algorithms, antenna pattern measurements, and detailed receiver tracking loop models to simulate code multipath errors. This article presents results for three environments - a semi-urban rooftop, an F-18 aircraft, and the aircraft carrier USS Eisenhower. Model accuracy is evaluated on the basis of multipath error statistics as well as time history amplitude and frequency content. In general, 1-σ error statistics for all scenarios match the experimental data to within 15 cm, and time history comparisons often show good agreement in terms of amplitude and temporal variability. Frequency content is compared on the basis of a cross-correlation metric, with values of 0.57 or better for at least 67% of the data points. We also demonstrate the application of the modeling tools for the evaluation of additional antenna placements, reflector identification, and the characterization of key multipath signal properties.