APPARATUS FOR THE OBSERVATION AND IDENTIFICATION OAPPARATUS FOR THE OBSERVATION AND IDENTIFICATION OF HELICOPTERS F HELICOPTERS

摘要

Apparatus for the observation and identification of helicopters by means of an FM-CW radar apparatus provided with transmitter means (1), antenna means (2) and receiver means (3). Blade flashes caused by the rotor blades are digitized by A/D converter (4) and processed by Fourier analysis means (5) and processor (6) in order to determine the range from a helicopter to the radar apparatus and the rotor symmetry characteristics. These symmetry characteristics, together with the blade flash repetition frequency yield a substantially unambiguous indication of the helicopter type. Fig. 2