Patent GB-729957-A (GB)
Title: Improvements in and relating to radio communication systems
IPC: H04J1/18
Filed: 1952-12-17
Abstract: 729,957. Radio signaling. INTERNATIONAL AERADIO, Ltd., GALLAGHER, P., TURNER, H., and PEAT, J. D. Dec. 17, 1953 [Dec. 17, 1952], No. 31995/52. Class 40 (5). A plurality of radio receivers operating at different frequencies are associated with automatic switching means whereby upon reduction or cessation of signal output from one receiver another is rendered operative. In the embodiment described, the receivers are rendered operative in succession until signal output is restored, and each receiver may be a diversity reception assembly. They may form part of a system in which, at the transmitter, a plurality of frequencies are available, the frequency of communication being changed merely by changing the transmitted frequency. The receivers RA ... RD are controlled individually by relays CA/3 ... CD/3 which, when operated, close contacts CA1 ... CD1 respectively to apply H.T. to the receivers and lock up over contacts CA2 . . . CD2. The commoned outputs of the receivers are applied to a relay T/5 and, for example, if receiver RA is in operation relay CA/3 is in the operated condition, the looking circuit being completed through closed contacts T2. An impulse source PS, for operating the uniselector S1 ... S4, is disconnected from pulsing relay P/1 and the wiper of bank S1 is open-circuited at contact T1, the uniselector being in the last home position. If output ceases from receiver RA, relay T/5 releases to release relay CA/3 at contact T2 and to energize the pulsing relay P/1 at contact T3 so that the drive magnet DM is energized through contact P1 and the uniselector steps to position 1. Relay CA/3 thereupon operates, through closed contacts Tl, and contact 1 of bank S1 to apply H.T. to receiver RA. As the latter produces no output the relay does not lock over contact T2, relay T/5 remaining deenergized and in due course the uniselector steps to position 2. Contact 2 of bank S1 is earthed through contact T1, relay CB/3 is energized, H.T. is supplied to receiver RB over contact CB1 and, if the receiver produces an output to energize relay T/5, contact T2 closes to lock relay CB/3, impulse source PS is disconnected at T3 from pulsing relay P/1 and contacts T4 close. The latter complete a self-impulsing circuit through the commoned contacts of bank S2 and the interrupter IC to step the uniselector round to the home position. Contacts 5 and onwards of bank S1 are commoned so that if none of the receivers is producing an output the uniselector continues, by self-impulsing, to search for an active receiver, as the bank S2 circuit is then broken at all the contacts CA3 ... CD3. Monitoring of the receivers is accomplished by operating a push-button PB which may be remote. It is assumed that each receiver RA &c. consists of two receivers RA1, RA2, &c. for diversity reception. Pushbutton PB energizes relay A/4 to open contacts A1 in the self-impulsing circuit of bank S2, to change over contacts A2 to charge condenser C, to open contacts A3 in one of the windings of a relay B/3 and to close contacts A4 to energize the pulsing relay P/1 so that the uniselector commences stepping. Banks S3, S4 are used to switch the H.T. to the eight receivers but not until contacts B2 are closed by operation of relay B/3. Relay B/3 is not operated unless PB is opened, whereupon A/4 is released to connect condenser C to relay B/3 which operates and locks over the contacts B3, T5 and A3. By this means, H.T. can be applied to any of the receivers, the uniselector being stopped due to the opening of contact A4. Relay B/3 is deenergized if the operating receiver fails to produce an output, its holding circuit being broken at contact T5 of the released relay T/5. The uniselector then commences searching again and PB is ineffective until relay T/5 is again energized.