High-resolution signal-in-space measurements of VHF omnidirectional ranges using UAS

Abstract

Abstract. In this paper, we describe measurement results of the signal-in-space of very high frequency (VHF) omnidirectional range (VOR) facilities. In aviation VOR are used to display the current course of the aircraft in the cockpit. To understand the influence of wind turbines (WT) on the signal integrity of terrestrial navigation and radar signals, the signal content and its changes, respectively, must be investigated. So far, only numerical simulations have been carried out on the frequency-modulation (FM) part of the Doppler-VOR (DVOR) signal to estimate the influence of WT on DVOR. Up to now, the amplitude-modulated (AM) part of the DVOR was not assessed at all. In 2016, we presented an unmanned aerial system (UAS) as a carrier for state-of-the-art radio-frequency (RF) measurement instrumentation (Schrader et al., 2016a, c; Bredemeyer et al., 2016), to measure and to record the true signal-in-space (both FM and AM signal) during the flight. The signal-in-space (which refers to time-resolved signal content and field strength, respectively) is measured and sampled without loss of information and, furthermore, synchronously stored with time stamp and with precise position in space, where the measurements were taken.

The Feasibility of Remotely Piloted Aircrafts for VOR Flight Inspection

“…References [14,15,18] presented their results in measuring flight guidance parameters in the time and frequency domains. The aim of the developed platform and experiments was to measure the influence of wind turbines on terrestrial navigation signals by analyzing the integrity of the RF signal.…”

“…RF standards, quality acceptance tests, safety monitoring, and the integration of UAs in airspace are questions that need to be addressed [8,16,17]. Regarding the integration of UAs in airspace, due to the increase in the maturity of UA systems, the use of UA flights in controlled airspaces has been reported without segregation of the airspace [18]. The UA, connected to a mobile network, transmits its position to a traffic management system that processes the UA position while at the same time showing the UA with the tracking data of manned aircraft.…”

Measurement and transformation of continuously modulated fields using a short-time measurement approach

“…Moreover, the development in the field of in-situ antenna measurements was elevated by the availability of advanced NFFFT algorithms, which offer advanced features such as the suppression of scatterers (Yinusa and Eibert, 2013;Eibert et al, 2015) or the consideration of dielectric and lossy ground (Mauermayer and Eibert, 2018). Antenna measurements with UAVs have been demonstrated for various frequency ranges (Paonessa et al, 2016;García-Fernández et al, 2017;Faul and Eibert, 2021a) and for applications such as the measurement of mobile radio base stations (Fernandez et al, 2018) or radio navigation signals (Schrader et al, 2019;Sommer et al, 2020). Specifically in the field of radio navigation, UAV-based antenna measurements can have a significant impact, when it comes to the verification of navigational aids (NAVAIDs) for aviation.…”