Patent GB-363981-A (GB)
Title: Improvements in or relating to automatic standby devices for wireless receiving apparatus
IPC: H04L15/26
Filed: 1931-09-18
Abstract: 363,981. Wireless signalling. CHAUVEAU, L. L. E., 79, Boulevard Haussmann, Paris. Sept. 18, 1931, No. 26191. Convention date, Sept. 18, 1930. [Class 40 (v).] The tuning of a circuit in a standby receiver is continuously varied over a prescribed range, the variation being interrupted for a predetermined period on receipt of a signal. Selector circuits are so arranged that the various elements of a required calling signal interrupt the tuning variation for progressively longer periods, the final element causing a complete interruption. In one arrangement, Fig. 1, the motor MC is coupled to the variable condenser CR of an aerial tuning circuit to continually vary its capacity. Any signals received are passed through valve L to energize the relay MN which closes the circuit of relay A through closed contacts 2, 3. The relay A locks up, causes the relay C to open the motor circuit, and energizes a slow-acting relay DM which after a period of twelve seconds opens at contact 3 the locking circuit of relay A, thereby de-energizing relay C to restart the motor which runs for at least two seconds while the finger d drops to close contact 2, and the apparatus reverts to normal. The circuit shown includes an alarm device responsive to three consecutive dashes of four seconds duration, the first of which is arranged to close contact S1, the second contact S2, and the third contact S3; If during the operation of DM a first dash operates S1, the relays B, DS operate exactly as A, DM already described but the finger d<1> takes one minute to rise during which relay B energizes relay C to keep the motor MC de-energized. If the second dash has meanwhile been registered by the closure of contact S2, the relay D is energized and is maintained by contacts 11 and 10, so that when contact 6 is closed by the finger d<1> after the first minute the operation of DS is repeated for one minute by contact 12 being closed. As finger d<1> starts rising it opens the circuit of relay D at the contacts 10, but the relay C is energized for a further minute by contact 9. If the third dash, constituting the final element of the correct signal is received, the contact S3 is closed permanently and the motor definitely stopped. An alternative arrangement is described, Fig. 2 (not shown) in which the slow-acting relays DM, DS are replaced by motor-driven cams. Clockwork or thermostatic devices may also be used. The system shown in Fig. 3 comprises tuning condenser CR, motor MC, and relays MN, A, DM, C as in Fig. 1 but the selector mechanism embodies a rotary step-by-step switch BA whose driving magnet AV is energized by the closing of contacts 62 by the pin d at the top of its stroke. Upon the first four-second dash operating contacts S1, relay E is energized and locked by contact 50, the relay G being energized by contact 51. The contact 58 energizes relay C to keep the motor stopped, while contact 56 connects positive to contact 62, and 57 connects positive to contact 2, so that when after twelve seconds the finger d closes contact 62 magnet AV is energized to drive the selector BA one step forward. Contact 3 is opened to de-energize relays A and DM, but after dropping, the finger d closes contact 2 to reenergize relays A and'DM which commences a fresh stroke. This continues as long as contact 57 is closed and the arm BR of the selector BA moves forward one step every twelve seconds. After one minute the arm BR reaches contact P5 and energizes the release magnet VR through contacts 52, 55, to return arm BR to its position of rest where it opens contact 61 to release the locked magnet VR. During this minute the motor MC is stationary. The second foursecond dash closes contact S2 to energize relay F which is similar to relay E, but through contact 55 connects the input of magnet VR to contact P10 on the selector which is not reached until the end of two minutes by the arm BR. Closure of contact S3 by the final dash stops the motor MC permanently as before.