Comparing predicted and measured time-variant DVOR bearing errors in presence of wind turbines
Résumé
The impact of scattering objects such as wind turbines (WTs) and other buildings on the VOR has been
addressed in various publications. Nevertheless, a practically feasible possibility to predict especially the Doppler
VOR bearing error during the building’s planning phase is challenging, since a electromagnetic model of that
facility must replicate its radiation with both CSB and SBO antennas in a complex scenario that is large w.r.t. the
wavelength. A new time domain method will be introduced to address this topic for dynamically disturbed
environments. Separating its frequency modulated (FM) and amplitude modulated (AM) content, the indicated
bearing is calculated subsequently by determining the corresponding phase difference. Within the research
project WERAN, an UAS-based (here: octocopter) platform with dedicated antennas, receivers and adapted
signal processing was developed. Using this device, it is now possible to measure separately small phase errors
on the 30Hz FM and AM signal components. According to the prediction, bearing errors due to existing wind
farms are now traceable at specific positions in the airspace. Hence, the numerical results can be validated by in
situ measurements of real DVOR signals-in-space in the environment of real WTs. The presentation will introduce
the numerical method and the measurement platform and give an overview on the validation cases.