Patent GB-555999-A (GB)
Title: Improvements in or relating to electric code signalling systems
IPC: H04L17/30
Filed: 1942-03-13
Abstract: 555,999. Selective signalling. STANDARD TELEPHONES & CABLES, Ltd., HARTLEY, G. C., and REYNOLDS, W. J. March 13, 1942, No. 3335. [Class 40 (i)] [Also in Group XL] In a start-stop signalling system, the transmission and distribution of the start, stop, and code pulses is effected by a relay chain under the control of a " pendulum '' relay having a vibrating armature which is released tc execute free oscillations and returned to a locked position after a predetermined number of swings. The system may be used for teleprinter working or for transmitting indications which are not recorded. Transmitter.-In the keyboard transmitter shown in Fig. 1, the depression of any key (except K and "letters") closes a circuit through one of the relays CA .... CO and either relay CZ or DS. The energized one of the relays CA ... CO, and the relay CZ, if this is energized, complete circuits for a combination of the storing relays V ... Z, which energize and lock up over contacts V<SP>1</SP> ... Z<SP>1</SP>. (For example, the depression of key D energizes relays CH, CZ over circuit 30, thereby energizing relays W, X, Z.) The pendulum relay P is normally energized over its lower winding and contacts. K<SP>2</SP>, H<SP>1</SP>, DS<SP>1</SP>, C<SP>22</SP> and holds it armature on contact PM. The depression of any key, by energizing relay CZ or DS, opens the circuit of relay P, which allows its armature to swing between contacts PS, PM. On the first closure of control PS a circuit is closed over contacts F<SP>1</SP>, D<SP>1</SP>, B<SP>1</SP> of the counting relays F, D, B, contact HR<SP>2</SP>, and relay A for the spacing winding S of the sending relay SR, which at contact 13 connects spacing current to line T, thus giving the start pulse. Relay A at contact A<SP>1</SP> prepares the circuit of relay B, which is energized where the relay P closes contact PM. Relay B prepares the circuit of relay C, which is energized where relay P next closes contact PS, and so on, relays A ... G being energized in turn. The circuits of relays B ... F include the spacing winding S or the marking winding m of the sending relay SR, according to the setting of the contacts V<SP>2</SP> ... Z<SP>2</SP> by the storing relays V ... Z, so that relay SR connects spacing or marking current to line T in the desired combination, the final pulse being a marking stop pulse through relay G. A key K and relays K, T permit the circuits to be tested. Receiver.-The code storing relays VV ... ZZ are selectively energized in turn under control of the connecting relays AA ... EE, a pair of relays HA, HB, and two pendulum relays PA, PB, of which PA merely serves to delay the release of PB, so that the storing relays are brought under the control of the line relay RR in the middle of each impulse period. Normally, relays HH, HHR, PA, PB, are energized. On the receipt of the start signal, relay AA energized over RRS, and relay PA releases its armatures, so that after a period relay PB releases its armature which closes contacts PBS, PBM, alternately thereby energizing the connecting relays BB ... FF in turn, each relay preparing the circuit of the next and disconnecting the previous one. The relay PB also energizes the slow-release relays HA, HB in turn, the periods of energization of these relays being so chosen that their contacts HA<SP>1</SP>, HB<SP>1</SP> connected in series are closed simultaneously for a short time at the middle of each impulse period, with the result that each spacing impulse is repeated by the line relay RR over contacts RRS, HA<SP>1</SP>, HB<SP>1</SP> to the storing relays VV ... ZZ in sequence. The energized relays VV ... ZZ lock up and close combinations of the circuits 1 ... 5 to energize the selector magnets, lamps &c. Specification 549,971, [Group XXXVII], is referred to.