GB147701A - Improvements in or relating to the reception of electric oscillations - Google Patents

Abstract

147,701. Ges. f³r Drahtlose Telegraphie. May 2, 1916, [Convention date] Wireless telegraphy and signalling; ware detectors.-In a system for the reception of undamped oscillations, the received waves of frequency n are used to excite an alternator or electro-static machine which possesses a natural frequency of N, thereby producing two new frequencies (n + N) and (n - N) which interfere in the detector circuit to form beats. The alternator 1, Fig. 1, consists of a stationary winding 2, excited bv oscillations received by the aerial 3, and a rotating winding 4 included in the aperiodic detector circuit 5, 6, 7. In the arrangement shown in Fig. 2, the secondary circuit including the winding 4 is not aperiodic, but is given two wave components of frequencies (n + N) and (n - N) by placing a condenser 11 in parallel with a small part of the inductance of the circuit. Atmospheric disturbances may be reduced by introducing two intermediate resonant circuits 12, 13, Fig. 3, tuped to frequencies (n + N) and (n - N) respectively, and variably coupling a common detector circuit to them by means of inductances 14, 15. In all the above-mentioned modifications beats of 2N are formed in the detector circuit. One of the circuits 12, 13 may be tuned to frequency n and coupled direct to the aerial, in which case beats of frequency N will be heard in the telephones. The secondary circuit 8 can, as shown in Fig. 4, be so arranged that it reacts again on the primary circuit 2 and produces two further frequencies (n + 2N) and (n - 2N). To this end, the circuit 8 is either wound as a short-circuited armature or it is tuned to frequencies (n + N) and (n - N). By giving the primary circuit 2, three wave components of frequencies n, (n + 2N), and (n - 2N), beats of frequency 2N and 4N are obtained. In all the arrangements described, the rotary circuit 4 may be made aperiodic by short-circuiting the rotary winding by an inductance, and coupling the circuit 8 thereto. The system may also be used for reception from tonic train transmitters. The machine 1 may be formed of a stationary and a rotating capacity, which influence one another periodically, in place of inductive windings.