Considered are the issues of automatic direction-finders efficiency ensuring at the Central vibrator ARP failure, which proposes to change the switching order of the vibrators of radio direction finder antenna system. An algorithm for changing the switching order of the antenna system vibrators is presented.

Keywords: radio direction finder, antenna system malfunction, increase of radio direction finder reliability

Article is devoted to the creation of direction finders for bearing earthquakes ionospheric precursors. Structural diagrams of two direction finders variants are given, their advantages and disadvantages are shown. Algorithms for the direction finders functioning and selection of ionospheric precursors are developed.

Keywords: radio direction finder, ionospheric earthquake precursor, signal selection, phased antenna array, wave, oscillation, phase, azimuth, angle of elevation

The paper is devoted to the problems of the aerodrome automatic direction finders accuracy characteristics checking. Disadvantages of the existing methods are shown. Recommendations to eliminate shortcomings are given, in particular it is proposed to take into account the orthodromic corrections to the measured values of the bearings during the flight tests.

Keywords: radio direction finder, flight tests, orthodromic correction, instrumental error