Patent GB-829784-A (GB)
Title: Improvements in or relating to teleprinters
IPC: H04L9/18
Filed: 1956-04-05
Abstract: 829,784. Type-printing telegraphy; secret telegraphy. SIEMENS & HALSKE A.G. April 5, 1956 [April 5, 1955], No. 10486/56. Class 40 (3). A start-stop teleprinter including a ciphering arrangement is provided with a break-in relay controlled by the line current during cipher transmission and arranged to stop the operation of the teleprinter if an interruption of the line current occurs while the stop pulse is being transmitted. For the normal plain language transmission the switch KG is in the position K and the switches LL, EU are in the position Ltg, KL respectively so that a circuit is completed to terminals 1, 2 through the receiving magnet EM, transmitter contacts LSK and the break-in relay GMS. If the message signals are to be ciphered, plain language intercommunication is used to decide the cipher perforated tape to be used, and the switch KG is then moved to the position G in which a circuit is completed to a relay U via contact KG5(G) and contact LSU closed when the motor switch is operated. A circuit for a plain language local record is completed over relay A, contacts KG2(G), KG3(G), EU2(KL), EU4(KL), the receiving magnet EM and transmitter contacts LSK. The plain language signals are transmitted by the relay A to the ciphering circuit so that in response to the start pulse, contact a completes a circuit for release magnets MI, MV controlling a sensing device for the perforated cipher tape and a correction distributer respectively, the latter opening contact KV2 before the end of the start impulse. The pulses from the sensed cipher tape control contacts LA operating a relay D provided with a biasing winding and the conjoint operation of contacts a, d control relay B operated at the centre of the element periods by contact KV1 of the correction distributer. The ciphered signal elements produced by relay B are passed over the line connected to terminals 1, 2 by a circuit through relay GMS, LL(Ltg), EU1(KL), EU3(KL), KG1(G), u2, b. The exploring arrangement for the cipher perforated tape includes a sixth feeler FK6 which after the termination of the cipher strip short-circuits keyboard controlled contact SK and stripcontrolled contact LSK so that no local record is printed. As relays A, D both remain operated and relay B remains operated the break-in relay GMS is released and stops the transmitter. Also a shutter which in the open position closes contacts KLK short-circuits the contacts SK, LSK so that no local record is printed. The signals transmitted by relay B are received at the distant station in a circuit including relay A and the contact a in conjunction with contact d controlled by the cipher tape operates relay B in accordance with the deciphered signals and at contact b operates the receiving magnet EM to produce the plain-text message. The circuit arrangement of Fig. 1 can also be utilized to produce a plain language perforated tape and printed local record, the switches LL, KG being moved to the positions LoK, K respectively. The circuit from the keyboard contacts SK passes through the winding of the magnet EM which controls the printing and also, if desired, a perforator. Perforated tape in cypher can be produced by moving switch KG to G, LL to LoK and EU to position VL. In this case a local record in plain language cannot be produced and the printer can be cut out when the switch EU is in the position VL. Also a plain-language perforated tape can be converted to a ciphered tape, and in local operation a ciphered perforated tape can be deciphered with the printing of the plain text version. In this case the ciphered tape is run through the tape transmitter with the switch key KG in position K until a predetermined code combination indicating the start of the ciphered message is detected. The switch is then moved to the position G and with the pre-arranged cipher tape in the ciphering device the plain language text is printed, and, if desired, can also be obtained as a perforated tape. In a modified circuit, Fig. 2 (not shown), the break-in relay is connected when the relay U, similar to that of Fig. 1, is in the sending position, and the operative holding circuit of the relay U includes a contact operated by the break-in relay and mechanically held except during the stop element. The transmission of spacing current by the operator at the distant receiver releases the break-in relay which in turn releases the relay U and switches the transmitter to the receiving condition. In a minor modification of Fig. 2, Fig. 3 (not shown), the break-in relay has two windings, connected in the line circuit and a local circuit respectively when the relay U of Fig. 1 has been switched over. The break-in relay is held by the local circuit during the start and five signal elements by a contact closed by the correction distributer and a further contact normally short-circuiting the line winding is opened by the distributer during the period of the stop element so that interruption of the line during this period releases the break-in relay. In a further modification of Fig. 2, Fig. 4 (not shown), the breakin relay has one winding which is energized by a local source during the start element and five information elements, but is held solely by the line current during the stop element. In a modification of Fig. 1, Fig. 5 (not shown), separate break-in relays are used for plain and ciphered signal transmission. In the former case the relay is connected to the line solely during the message transmission. In the latter case i.e. for ciphered transmission, the break-in relay is in a transmission circuit including the contact b of the ciphering relay B of Fig. 1 and its armature is mechanically held except during the stop element period. If as described for Fig. 1, relay B remains operated, or the line circuit is opened by the distant operator, during the stop element period, the break-in relay releases and the circuit is switched over to the receiving condition.