Helicopter navigation system

摘要

In a system for use in helicopter navigation antennas are carried at the free ends of each of the blades of the rotor of the helicopter. Radio waves transmitted by a beacon at a known location on the ground are received by the antennas and phase modulated by their rotation. On the rotor the signals are amplified and mixed with oscillations from local oscillators and are detected with the aid of reference signals from the local oscillators. By means of slip rings and contact brushes the signals are introduced into the body of the helicopter where they are first multiplied with each other and then filtered so as to produce phase-modulated signals with a carrier suppressed which are supplied to an electroluminescent diode illuminating a rotating-disc light modulator with a light-transmitting function which is analogous to the phase modulation of the signals received by the antennas. The light beam passing through the disc is integrated in a vidicon and displayed on a screen.