Patent GB-386676-A (GB)
Title: Improvements in or relating to secret telegraphic systems
IPC: H04L9/38
Filed: 1931-07-17
Abstract: 386,676. Type-printing telegraphy. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. July 17, 1931, No. 20542. Convention date, July 17, 1930. [Class 40 (iii).] In a type-printing telegraph system in which the signals comprise combinations of impulses of opposite polarities, or of impulses of current and no current, each successive signal is differently coded for secret transmission by a mechanical device which changes the current value of different elements of the impulse combination, and at the receiving end the signals are applied to the recording apparatus through a mechanical decoding device adjusted in conformity with the coding device at the transmitter. In a modified system, the order in which the current impulses of a signal combination are sent to line is varied in conjunction with the variation of the current value or polarity of the impulses of the signal combination. Transmitting arrangements (Fig. 3). The depression of a keyboard lever Te positions code bars 1 . . 5 and contacts k1 . . k5 according to the uncoded signal, and, through a universal bar 6, closes a contact ak operating a relay AR which at ar2 operates the magnet AM of a transmitting cam shaft SW, and at ar1 sends a start impulse through the normally closed contact sk6 and the sending relay SR. During the rotation of the cam shaft, the cams F1 .. F5 close in succession the contacts sk1 . . sk5, through which the relay SR operates to transmit impulses to the line. Simultaneously with the transmission of the fifth impulse, the cam F7 closes contact. sk7 energizing the release magnet FM of the shaft AW which, through gearing, rotates cams N1, N2, to a position to alter the polarity of one or more of the impulses of the succeeding signal and to rotate to a new position a shaft CW carrying cams Nw1 .. Nw6 .. setting change-over switches 1w .. 6w .. varying the order in which the signal elements of combination are transmitted to the line. In the arrangement shown the cams N1, N2 .. are positioned so that the potential value of 'the first impulse is reversed at the contact 1t, and by the cams Nw1 .. Nw6 .. the change-over switches 1w, 6w are set so that the order of the transmission of the first and fifth impulses of the signal are inter- -changed. -In Figs. 1 and 2, (not shown) the change-over switches 1w .. 6w and the cooperating cams are omitted from the system. Receiving arrangements (Fig. 4). The received coded impulses are applied to a line relay CER operating a contact cer, and, the decoding cams N1, N2 .., Nw1, .. Nw6 .. are adjusted in - conformity with the position of the corresponding cams at the transmitting end. The changeover switches 1dw .. 6dw .. are arranged so that, as compared with the interchanging by the transmitter switches 1w .. 6w .., the lines l1 .. l5 are changed over in the reverse order before being applied to the decoding arrangement which evaluates the individual impulses to be applied to the receiving apparatus. On the arrival of the start impulse, contact cer reverses and through the normally closed contact ek6, energizes the start magnet AMF of the cam shaft F so that the contacts ek1 .. ek5 transfer the received impulses to the change-over arrangement 6dw .. 1dw and by the setting of the contacts 1dt .. 5dt, the condensers C1 .. C5 are charged in accordance with-the decoded impulses set up at the transmitter. Towards the end of the revolution of the cam shaft F, cams F<1>1 .. F15 close simultaneously the contacts ek<1>1 .. ek<1>5 through which the relays R1 .. R5 are selectively operated -by the charges stored in the condensers C1 .. C5. Simultaneously the cam F7 on the shaft F energizes the start: magnet FDM of the code cam shaft to set the decoding cams for the next signal, and also the magnet AMG of a cam shaft G which on the opening of contact gk6 sends a start impulseto the printer receiving magnet EM which is successively operated in accordance with the setting of the contacts r1 .. r5 of the relays R1 .. R5. Modified receiving arrangement. Fig. 7 shows an arrangement in which the decoded impulses' are applied to a single relay R controlling the printer receiving magnet. The start impulse operates relay CER energizing the start magnet AM of the cam shaft V closing in succession sets of double contacts ek1, ek1<1> ... When an uncoded current impulse arrives, contact cer is in the position shown, and assuming it to be the first impulse, a circuit is completed from positive battery, contact n1, and through' relay R in a direction which closes its contact r and sends an impulse through the magnet EM. Assuming the second impulse to have been coded and to be received as a current interruption, cer is released, but on account of the reversed position of the contacts n2, n2<1>, current passes from positive battery, contact n<1>2, upper contact cer to operate relay R, and send an impulse through the receiving magnet EM. In a further modification, Fig. 8, similar to that shown in Fig. 4, the line receiving relay CER reverses its contact cer on reception of the. start impulse, energizing the coupling magnet AM1 over the normally closed contact ek6. A short interval afterwards a second camshaft (not shown) is set into rotation and at contact g6 the start impulse is sent to the receiving magnet EM. The incoming impulses, applied through the contacts ekl .. ek5, close in succession circuits to polarized relays R1 .. R5 situated in circuits controlled by contacts n1, n1<1>, .. n4, n4<1>, operated by a decoding cam disc (not shown). The contacts r1, r2 .. r5 selectively operated by the relays are explored in succession by the cam-controlled contacts g1 .. g5, and finally contact g6 is closed to apply the stop impulse. Assuming that the second impulse has been reversed at the transmitter, and that it arrives as a current interruption, the contact cer is reversed, but on account,of the reversed positon of the contacts n2, n<1>2<1>, by the decoding cam disc, current passes through relay R2 in the direction to operate its contact r2, and the magnet EM receives an impulse when the cam contact g2 is closed. The decoded impulses are applied in succession to the magnet EM by which the receiving instrument is actuated to print the decoded character.