Abstract. Field strength or signal-in-space (SIS) measurements have been performed by using manned helicopters, aircrafts or from ground level using extendable masts. With the availability of unmanned aerial systems (UAS) such as multicopters a new versatile platform for SIS measurements is deployable. Larger types show up to eight individually driven electric motors and controllers (therefore called octocopter). They provide the ability to fly along predefined traces, to hover at waypoints and to initiate other actions when those have been reached. They provide self-levelling and stabilisation and moreover, they may gear at a point of interest regardless of their actual position, e.g. during their flight around a tower. Their payload mainly depends on the platform size and allows integration of complex measurement equipment. Upgrading their navigation capabilities including state-of-the-art global navigation satellite system (GNSS) and ground station transmitter (real-time kinematic – RTK) enables precise localisation of the UAS. For operation in electromagnetic harsh environments a shielding can be considered and integrated into the concept. This paper describes concept and design of an octocopter and its instrumentation, along with applications in recent projects, in which we measure and validate terrestrial navigation systems applied in air traffic and the weather forecast services. Among those are instrumentation landing systems (ILS), VHF omnidirectional radio ranges (VOR), airport traffic and weather radars as well as military surveillance radars, and UHF wind profilers. Especially to investigate the possible interaction of VORs and radars with single wind turbines (WT) or wind power plants has become a major request of economy, military and politics. Here, UAS can be deployed to deliver measurement data investigating this interaction. Once developed and setup to a certain extent, UAS are easy and cost-efficient to operate. Nonetheless, due to their compact size, UAS will have rather low interaction with the electromagnetic field to be measured compared to the operation of manned helicopters.
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.
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