Improvements in or relating to navigation aiding radio receiving systems

摘要

503,471. Directive wireless systems. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. Oct. 10, 1938, No. 29326. Convention date, Oct. 8, 1937. [Class 40 (v)] A direction-finding receiver, e.g. a "homing" receiver, in which the phase of an input signal to the receiver is periodically reversed, is provided with an oscillograph indicator to which dephased deflection voltages are applied causing the indicator spot to describe a closed path at the frequency of the phase reversal, the receiver output being fed to the oscillograph so as to cause the spot to depart from its normal path to an extent depending upon any amplitude change occurring on phase reversal. In the honiing receiver shown in Fig. 6, the pick-ups from the frame and open aerials, a and b, are fed in parallel and in push-pull respectively to the two amplifying valves V1, V2 which receive anode voltages from the local oscillator G, the voltage of which is such that the two valves are rendered alternately conductive thus periodically reversing the phase of the open aerial pick-up. The amplifier output is fed through the transformer T, rectified, and passed through the resistance W, the voltage across which is applied to the accelerating anode A of the cathode-ray tube f to control its deflection sensitivity. Deflection voltages in phase quadrature are derived from the generator G and applied to the deflection plates P1, P2 causing the cathode-ray beam to describe a circle, the frequency of rotation of the beam being equal to the phase-reversal frequency. When thevehicle is "on-course" the amplitude of the combined pick-ups is constant for both positions of the phase-reversal means and the resultant oscillograph trace is a circle, but for "off course positions the amplitude differs for the two positions giving two semicircles of different diameter Fig. 5. Alternatively the distorted trace could be produced by causing the amplifier output to modulate the deflecting voltages and the 'amplifying valves could be replaced by diodes or other rectifiers.