MEASUREMENT OF COORDINATES OF UNMANNED AERIAL VEHICLE RADIO BEАCON

An experimental system for measuring the parameters of the flight trajectory of its own object-radio beacon, in particular, in the unmanned aerial vehicle (UAV) is developed and tested. Passive radio-location system is used. The difference-phase, difference-time and difference-frequency methods are compared. The first one provides the sufficient precision, not more than 1 deg. in the range of 30 to 140 deg. The phase measuring device is based on chip AD8302, operating at the frequency range up to 2.7 GHz. The fulfilled assessment has underlined the ability to measure the trajectory of objects-radio beacons in range of several kilometers. 

A set of measurements has performed under different conditions in near ground and free atmosphere. UAV flight in air, far from the surface of ground, provided a sharp decrease of an influence of surrounding radio noises. The deviation of the UAV flight line from the vertical axis of the antenna is possible due to the deflection of the UAV  from this axis at altitudes of 100 or more meters due  to  strong winds  at  these  altitudes and due  to  the possible deviation of  the  antenna  axis  from  the vertical. Obtained experimental dependences of the phase difference on flight time of the UAV are satisfactory and describe the dependence of the phase  difference  of  radio waves  at  433 MHz.  The  narrow  RF  filter  eliminates  the  impact  of most  RF  sources  such  as  radio broadcast  stations,  industrial  noise. Geometrical  shortcomings  can  be  avoided  by  inclusion  of  photodetectors  and  horizontally leveling of antennas. The obtained results envisage the system’s suitability for localization of objects with radio beacons onboard in a range of several kilometers as well as the possibility of the proposed methodology application for measuring the coordinates of unknown UAVs and ballistic objects.