Fuente: Wipo "digitalization" 780,947. Code telegraphy. HAZELTINE CORPORATION. March 23, 1954 [March 30, 1953], No. 8412/54. Class 40 (3). A pulse - code communication system in which an error in a group of code combinations of pulses representing characters is automatically corrected, comprises a transmitting arrangement in which a number of character code combinations are stored for the purpose of deriving a check code combination of elements uniquely representative of predetermined digital relations of the elements in the character groups which are transmitted and followed by the check group, and a receiving arrangement in which the received pulse groups are stored and a check group derived from the character groups as received is compared with the check group as received to enable a faulty code element to be corrected before the character groups of pulses are applied to recording apparatus, such as a teleprinter. In the system described five signals each comprising five code elements are stored to derive a five-unit check signal. Transmitting-arrangements.-At the start element of a code combination from the transmitter 50, winding 63a is de-energized and at closed contact 63b a pulse generator 64 is triggered into operation for the period of a signal combination and energizes a winding 71a which at contact 71b brings into operation a pulse generator 65 and at contact 71c connects the output of the transmitter 50 via a normally closed contact 52b to a shifting register 51 having twenty-five storage circuits numbered 30 ... 3. The generator 65 produces sampling pulses operating winding 52a so that contact 52b is intermittently opened, and closed at approximately the middle of the pulses produced by the transmitter 50 and also produces pulses applied to step forward in sequence the pulses after they have been registered in the circuit member 30. After five more combinations have been stored on the shifting register 51 the impulses are transferred simultaneously to a message digit register by the action of a keying pulse generator 67 operated when 25 pulses have been counted by the counter 66. The pulses set up in the register 53 are also applied to a check-digit computer 55 comprising sensing members 1a . . . 16a set into operation by a driving mechanism controlled by the generator 67. Each of the members 1a . . . 16a is arranged to examine fourteen of the code pulses stored in the register 53, the member 16a, for example, examining pulses 17 ... 30, as indicated by the table shown in Fig. 3. The remaining members 8a ... 1a examine other mutually different sets of pulses as displayed by the table and the arrangement is such that a particular pulse is examined simultaneously by two or more of the members 1a . . . 16a-pulse 7, for example, being examined by members 1a 2a, 4a, and pulse 30 by members 2a, 4a, 8a, 16a. Further, a different combination of the members 1a ... 16a is associated with each of the pulse elements examined. The pulses detected by the members 1a . . . 16a are passed to odd-even pulse counters 1b . . . 16b providing a positive or zero output in the case of an odd or even number of pulses in the fourteen elements examined. The check elements or pulses are applied to storage devices 1, 2, 4, 8, 16 of a message digit and check digit register to which the pulses from the register 53 have already been applied. The 25-message elements together with the 5 check elements are passed via distributer 58 set into operation by a driving mechanism 59 controlled by the generator 67. The sequence of elements is prefixed by a two-fold synchronizing signal producing marking and spacing elements of unit length apart from a marking impulse of 1¢ units from segment 69 and a spacing impulse of 2¢ units from an earthed segment 70. The signals are sent from transmitter 61 as frequency shift modulations. A reset pulse generator 68 provides pulses at appropriate times to restore the registers 53, 54 and computer 55 to reference conditions in preparation for the n