Measurement Techniques

Methods have been developed for measuring angular coordinates and determining the location of radio emission sources using a panoramic digital direction finding detector located on board an aircraft-type unmanned aerial vehicle. The angular coordinates of the objects were measured by the phase method using the fast Fourier transform and synchronous spectral analysis of signals in the receiving channels while eliminating the ambiguity of the measurements of phase incursions by finding their multiplicity indices. The methodology for determining the location of radio emission sources is based on a rational choice of positions for measuring the directions of arrival of signals at various points on the flight path of an unmanned aerial vehicle according to the criterion of the minimum standard deviations of the source location estimates. The accuracy of measuring the angular coordinates and determining the location of objects in the conditions of a radio measuring range is analyzed. The measurements were performed at frequencies at which the level of background radio emissions is minimal for the operating frequency range of the detector-direction finder and does not lead to the appearance of abnormal errors. When determining the location of radio emission sources, the movement of an unmanned aerial vehicle with a direction-finding detector on board was carried out in an arc with a maximum notch angle of the bearing of 120° and in a spiral when setting directional angles in the turning points of the route according to the criterion of minimizing the dispersion of position determination. It was found that when calculating the phase incursions of signals in the frequency range 30–3000 MHz, the error in measuring the angular coordinates of radio sources is within 3.3–4.9°; for a signal-to-noise ratio 15 dB at the receiver input, the accuracy of the experimental estimate of determining their location is 2.2–13.8% of the range. Detector-direction finders of signals placed on unmanned carriers are used to monitor the electronic environment. Information on the angular coordinates and location of radio emission sources, invariant to changes in their operating modes and parameters of emitted signals, is used for spatial selection and recognition of objects.