Patent GB-907412-A (GB)
Title: Improvements in or relating to methods of and apparatus for the production of extended cipher strips of a very long period for enciphering machines
IPC: H04L9/38
Filed: 1959-02-23
Abstract: 907,412. Code telegraphy. HELL, R. Feb. 23, 1959 [Feb. 21, 1958], No. 6215/59. Addition to 817,761. Class 40 (3). In a ciphering arrangement for signals of an equal-unit code, which is mainly equivalent electrically to the arrangement claimed in the parent Specification, a number of unequal length tapes carrying code combinations of the equal unit code in numbers which are prime to each other, are stepped at the same rate past a transverse scanning arrangement which examines different code positions of the various tapes, and when a prearranged code distribution of perforations is formed from the scanned positions of the assembly of tapes, a positive or negative pulse from a train of alternating pulses of positive and negative polarity which conjointly occur at the same frequency as the transverse arrays of perforations are scanned, is generated and stored, and the generation of a number of these positive and negative pulses, equal to the number of elements in the code, controls means by which the generated code combination is passed to ciphering device or punched in a tape to form a cipher strip. A number of identical gear-wheels 6 . . . 10 on a shaft 5 driven by gear-wheels 2, 3 from a motor 1 have sprocket teeth 11 engaging equallyspaced feed perforations 12 in tapes 13 . . . 17 of different lengths carrying sequences of perforations according to 5-unit code combinations. A sensing arrangement comprising five lamps 18 . . . 22 and five banks 23 . . . 27 of photocells, each bank having five cells of which one only is arranged to be associated with a single specified perforation position of the respective individual tapes 13 . . . 17. The numbers of the feed perforations 11 formed in the tapes 13 . . . 17 are all prime to each other to form a lengthened recurrence cycle. A disc 29 has slots 31 and teeth 32 co-operating with a photocell 35, whilst perforations 30 are associated with a second photo-cell 34, the arrangement being that the holes 30 are equal in number to that of the teeth 11 and are located circumferentially approximately at the centre of the notches 31 and teeth 32. As shown in Fig. 2, the photo-cells 23 . . . 27 are linked via amplifiers 36 to two condition devices 37 which in response to a perforation in the tape 13 . . . produce +ve potential on lead 39 andve potential on lead 38, and vice versa when there is no perforation. Switch members 32 are set to engage contacts 43, 46 in accord with a prearranged code representative of perforations and no perforations in the 1st . . . 5th code perforation positions allocated to the five tapes 13 . . . 17, and, as indicated in Fig. 2, three prescribed code combinations are set up on the three columns of switch members 52 in conjunction with terminals (43, 46), 44, 47) and (45, 48). When a code combination of five perforations identical with the prescribed arrangement is detected, all the rectifiers 53 are connected to negative outputs of the devices 37. Also, a perforation in the disc 30 operates cell 34 and a switch device 65 to produce a negative voltage on the lead 66 and if the rectifiers 53 are all similarly biased by the detection of the predetermined combination, a circuit is completed from source 62 through resistors 59, 69. The fall in potential at the resistor 69 operates an electronic switch 72 to pass a pulse via gate 74 to a closed ring often two-stage devices 76 . . . 85, the pulse being operative to change the condition of the two condition device which receives the pulse, and this operation changes over the next two condition device of the ring 76 . . . 85. The photo-cell 35 associated with the notches 31 and teeth 33 of the disc 29 operate the switch member 94 to produce +ve and - ve pulses in alternation, a positive or negative pulse being generated almost simultaneously with the pulse from the photo-cell 34. If a positive pulse is applied over conductor 92 simultaneously with a pulse from a switched two-conduction member 76 . . . 85 of the ring counter, an associated two-condition device 95, 97. . . 100 or 141 . . . 145 is triggered to control, through respective associated gates 118 . . . 122 and 123 . . . 127, and also circuits 133 . . . 137, the magnets 113. . . 117 of a perforator which produces 5-unit combinations of perforations to constitute a cipher strip which is used in conjunction with a tape perforated according to the plain text of the message to produce the ciphered signals for transmission. The pulse applied when the device 80 changes over, is also applied to gates 102, 103, of which the former is open when the previous code combination has been perforated. Assuming the gate is open, a switch device 104 changes over and produces a negative voltage on line 105 and positive voltage on line 106. The voltage on line 105 is differentiated by device 107 and applied over line 108 and gate 109 to operate the start-magnet 111 of the perforator. The pulse from 107 is also passed through gate 138 to reset the twocondition devices 141 . . . 145. The negative voltage on the line 105 opens the gates 118 . . . 122 to pass the pulses from the operated twocondition devices 95, 97 . . . 100, whilst the positive voltage on the line 106 blocks the gates 123 . . . 127 associated with the switch devices 141 . . . 145 controlled by the elements 81 . . . 85 of the ring counter. When the element 85 operates it controls gate 160 to reverse the voltages in lines 105, 106-the negative voltage on line 106 operating the start magnet 111, resetting the switch devices 95, 97 . . . 100, and opening the gates 123 . . . 127, whilst the positive voltage on the conductor 105 closes the gates 118 . . . 122 associated with the switch device 95, 97 . . . 100. As pulses indicative of the prescribed detections may be passed via the counter 76 . . . 85 to the storage devices 95, 97 . . . 100 and 141 . . . 145 more rapidly than they can be accepted by the perforator, a safety circuit is included to prevent pulses passing to storage for a period of about 50 m secs. after perforation of the stored elements has begun. When the sixth detecting pulse is received, the element 81 is triggered and passes over line 164 a pulse which switches a two-condition device 146 producing a pulse opening a gate 148 to pulses from the timing switch device 65 which step a sixteen position counter 151. After four steps, a gate 152 is operated and returned to its normal condition at the end of sixteen steps. From the 4th to the 16th steps, the device 152 prepares a gate 157, and when four further detection-indicating pulses received during the operation of the counter 151, have triggered the devices 82 . . . 85, a pulse over conductor 158 operates gate 103 so that gate 157 passes a pulse to close the gate 74 to any detected pulses which could alter the setting of members 95, 97 . . . 100 whilst perforation of their previous settings was being carried out. The pulse from the member 85 of the second storage group also operates gate 160 to change over the switch device 104 to control the perforation of the cipher tape according to the settings of the members 141 . . . 145. Further when the switch member 76 is operated the device 146 is switched and the counter is operated to prevent any adjustment of the members 141 . . . 145 whilst perforation of the cipher tape is taking place in accordance with their settings.