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Session 10: UAV Operations and Flight Inspection Applications

Employing UAS to Perform Low Altitude Navaids Measurements
Jochen Bredemeyer, FCS Flight Calibration Services GmbH, Germany; Thorsten Schrader, Physikalisch-Technische Bundesanstalt (PTB), Germany
Location: Regency Ballroom
Date/Time: Thursday, Apr. 19, 1:35 p.m.

An unmanned aerial system (UAS)-based measurement system to supplement or replace ground inspection of ILS (LOC, GP) and (D)VOR is described. This platform allows quasi-stationary hovering not only in areas normally accessed with mastequipped vehicles for ILS ground inspections, but also in critical areas accessible only with a flying platform. The calibrated and operationally robust UAS is an ideal tool for setting up system and antennas of new installations, thus accelerating the commissioning of ILS Localizers and Glideslopes prior to certification by flight inspection. Measurements are now also possible in locations where it is not practical or safe to measure with a conventional flight inspection system, e.g. to generate measurement data for electromagnetic simulations.
A conventional multicopter is used as a carrier UAS. Dedicated antennas were designed to respond to both electromagnetic and mechanical requirements for the respective wavelengths of 3m (LOC, VOR) and 1m (GP). The UAS features a light-weight dedicated dual ILS LOC/GP (VOR, GBAS) receiver and recorder payload based on a miniaturized, FPGA-controlled system handling large bandwidth data streams in real-time. All components, i.e. antennas, RF and signal processing hard- and firmware were specially designed to meet the application’s requirements.
A particular challenge is to separate the desired ILS/VOR signal-in-space from near field effects generated by the UAS itself. Effects that must be carefully removed from the incoming ADC-sampled signal is e.g. propeller induced amplitude modulation, or the short-term dynamics of a flying UAS.
In contrast to conventional ILS receiver technology, the raw channel bandpass signal-in-space covering the complete channel bandwidth is sampled and directly recorded at a high data rate. Signal postprocessing then extracts all essential parameters of interest. Responding to a main user requirement, essential ILS /VOR parameters are down-linked in real-time. This was implemented through combined hardware and software signal processing. A radio link is connected to a tablet PC on the ground for sensor control and the display of relevant signal parameters.
The paper describes the experience gained with the system, and provides recent measurement results obtained from ILS Localizer/Glidepath and VOR installations.



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