GB467892A - Improvements in or relating to direction finding radio receiving systems - Google Patents

Abstract

467,892. Directive wireless signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and WRIGHT, G. M. Nov. 20,1935, No. 32121. [Class 40 (v)] In a direction-finding system employing a plurality of directional aerials, or an aerial system including a directional member in which the phase of connection to the receiver is periodically changed, the signals are fed successively to, and compared by an indicator, e.g. a cathode ray tube, so arranged as to respond not merely to integrated signals but to distinguish between derived and interfering signals. In Fig. 3, 1 and 2 are mutually perpendicular rotatable frames tuned by condensers 3, 4. The diodes or other rectifiers 12, 14 are alternately made conducting by low frequency voltage supplied by the transformer 17, 18, the rectifiers alternately connecting the frames to the tuned circuit 6, 7, coupled to the receiver 9 by coil 8. 10a is a cathode ray indicator, one pair of plates being supplied from the receiver 9 and the other pair from the source of low frequency. Diodes 20, 21, which are saturated, are for current limiting to reduce the necessary size of diodes 12, 14. The pattern produced on the screen of the cathode ray tube consists of two sections corresponding to the output from the two frames which are rotated until the amplitudes of the deflections are equal ; this gives the direction of the incoming signals. The general level of the wanted signal can be seen on the cathode ray tube despite any deflections due to interference. In the modification shown in Fig. 5, the loop aerial 25 has its phase reversed by the double diode 32 which is switched by a low frequency voltage supplied by the transformer 13, 17. The output from the tuned circuit 34 is added to the output from the non-directional aerial 26 and fed via the amplifier 54 to the receiver 9 and cathode ray indicator 46, 47, 48, 49. The indications on the tube are adjusted to equality by rotation of the loop aerial in the same manner as in Fig. 3.