Direction-finding method and system

Abstract

High-frequency waves transmitted by a rotating antenna array at a ground tion are intercepted by an airborne receiver for photoelectric evaluation by one or more discs whose light transmissivity, by translumination or reflection, varies periodically according to a sinusoidal law in one diametral direction while being constant in another diametral direction orthogonal thereto. The disc or discs are rotated at a speed corresponding to that of the transmitting antenna array, under the control of periodic synchronizing pulses, and are illuminated by a flux modulated by an electrical signal derived from the incoming wave, this signal containing a phase component dependent on two spatial coordinates such as elevational and azimuthal angles determining the relative position of the ground transmitter and the airborne receiver. The flux optically filtered by any such disc has a peak at a point determined by the spatial coordinates whereby the relative position can be visualized by a display device such as a vidicon camera and an associated oscilloscope screen. Parasitic components due to reflections from moving objects can be suppressed by integration of the optically filtered flux over a limited period.