Improved keying arrangement for transmitters employed for direction finding purposes

摘要

493,683. Wireless transmitting-apparatus. LORENZ AKT.-GES., C. March 11, 1938, No. 7647. Convention date, March 11, 1937. [Class 40 (v)] Direction transmitters, as used for marking-out a navigational course, are keyed at predetermined frequencies and with given signal-to-gapratios, as indicated at a, and b in Fig. 1, by electromagnetic relays which are suitably inter-connected and timed. As shown in Fig. 3, the relays I, II, timed respectively by resistances W1, W2, control the consecutive keying at 21 of the beam aerial E, whilst a third relay III, switched in at S, allows a change from one keying frequency to another. When the starting switch A is closed, the relay I is first energized over the resistance W1 and contacts 3, 2. It closes contact 1 to energize relay II over resistance W2, thus opening contact 2 and de-energizing relay I, which, after a certain interval, opens contact 1 in the circuit of relay II. The latter releases, after a certain period, to close contact 2. The relay I is then energized and the cycle is repeated. If the relay III is included, the keying frequency is reduced.