Patent GB-665895-A (GB)
Title: Quick acting pulse recording device and application to teleprinter systems
IPC: H04L12/00
Filed: 1947-12-23
Abstract: 665,895. Telegraph exchange systems. STANDARD TELEPHONES & CABLES, Ltd. Dec. 23, 1947 [Oct. 26, 1946], No. 33968/47. Class 40 (iii). A device for receiving and storing trains of five-unit type telegraph signals or like impulses comprises a distributer chain of discharge gaps having delay means individual to each of the distributer gaps to cause said gaps to operate independently in timed sequence when they are all primed simultaneously. The description relates to a register for a telegraph exchange system. Preparing the register to receive. In the normal state negative battery is received on leg r, and transmitted on leg t. When the distant teleprinter is ready to transmit, positive battery is received on leg r, operating the relay Rr to R and operating relay Ar via the rectifier RD2. The contact Ar1 completes a slow-release circuit so that the relay Ar holds during normal message signalling. At Ar2 relay Br is operated and this is also slow to release as an additional safeguard in case the relay Ar should momentarily release during signalling. At Br2 relays Cr ... Fr operate over Qr1 normal and their contacts charge condensers C1 ... C5, applying negative bias to the discharge tubes 1... 10. The slow-to-operate relay Qr then operates but relays Cr ... Fr are locked over Fr4 and Rr on R. Receiving a directory code. The code is assumed to comprise five characters in the normal five-unit start-stop code, and when the first start element is received on leg r, relay Rr operates to T, releasing relays Cr ... Fr. The condensers C1 ... C5 discharge slowly because of their associated resistors and the time-constants are so arranged that the tubes 1 ... 5 strike in the middle of each code element, their anodes being supplied over Br2. The tubes 6 ... 10 tend to strike similarly but their anodes are connected to battery only when the relay Rr is on T and so only those tubes 6 ... 10 corresponding to received space code elements will actually fire. Those tubes which do fire, by their consequent cathode unbalance fire associated storage tubes TM1 ... TM5 which are so biased as to remain conducting. When the last code element of the first character has been received tube 5 fires and operates its anode relay Gr which at Gr1 operates relay Hr which in turn at Hr4 operates Ir and locks both relays. The next character is thus routed to tubes TM6 ... TM10 (not shown). Relays Cr ... Fr release at Gr2 and when the tube 5 is extinguished at the end of the last code element Gr releases. The following four characters are similarly dealt with, the trains of operations being initiated by their respective start elements as above and the characters being routed to successive banks of tubes TM11 ... TM15 (not shown), TM16 ... TM20 and TM21 ... TM25 by relays Jr ... Or. When the last code element of the final character is received tube TM25 strikes and also tube 5. which operates its anode relay Gr. Relay Pr then operates over Gr1 up, Ir4 up, Kr4 up, Or4 up, and locks over Prl up, lead c, Br1 up. At Pr4 the anode potential is removed from tubes 1 ... 10 so that any further signals received have no effect. Retransmission may be automatic but as shown a key TC is manually closed and released to operate a stepping magnet SP and drive a rotary selector switch from its housing position N to position 1. It is then driven, under control of 50 # current from a suitable source S18, via bank b wiper and steps round at 20 ms. intervals. The code element conditions stored on tubes TM1 ... 25 are sequentially transferred via bank a to the coil Tra and so retransmitted. Earthed contacts such as 1 on selector bank a insert start elements and blank contacts such as 7 insert stop elements. The switch stops on contacts 36 as the b wiper does not now connect the 50# source to the stepping relay SP. When the distant operator sends a long negative release signal relay Ar releases, the holding circuit being shunted by the rectifier RD1, and in turn releases relay Br. The A.C. source S18 is reconnected to stepping relay SP at Br5 and the switch steps to its homing position N, ready for a new transmission. Relays Hr ... Or release at Br1, and Qr at Br2, thus returning the register to normal.