Patent GB-732162-A (GB)
Title: Means for detecting errors in apparatus for analysing coded signals
IPC: G06F11/08
Filed: 1953-03-20
Abstract: 732,162. Copying-telegraphy; code telegraph systems. EASTMAN KODAK CO. March 20, 1953 [March 21, 1952], No. 7700/53. Class 40 (3). A copying-telegraph system in which characters are represented by equal numbered groups of code signals selected from a predetermined number of positions and the selective combination results in a potential on a terminal corresponding to the character represented by the group of signals, incorporates an arrangement for indicating when a code group is faulty and contains less than the prescribed number of signals. In the arrangement shown in Fig. 1 which is basically similar to that described and, shown in Specification 711,498, the cord perforations in a tape 11 corresponding to the character are sensed by brushes 10 and negative impulses are applied to render selectively non-inductive the left-hand sides of twintriode flip-flop circuits 14 whose left-hand sides are normally conductive. The operation of a circuit 14 controls its associated diode 16 to make valve 17 conducting and to initiate the action of the circuit 19. The left- and rightanode circuits of the double-triodes are selectively connected via members 21 corresponding to the coding of a character to the guide of an associated valve 20 which can be made conductive only if signals are applied simultaneously from all the flip-flops 14, and the valve 20 thus selected applies a potential to a signal synthesizing circuit 19 which through control circuits 38, 39 and an electromagnetic driving circuit 23 operates styli 24 to mark the tape 25 according to the character to be reproduced. At the end of a character, a valve 26 is operated to reset the diodes 16 and the circuits 14. The error-indicating arrangement comprises a number of pentodes 27 having their grids connected to the normally-conducting, i.e., left-hand, sides of the double-triodes 14, and the operation of a tube 14 renders its associated pentode 27 conducting, thereby producing for each pentode a potential drop of, say, 20 volts by means of the resistor 28. The plate circuits of the pentodes 27 are connected in common to the grid of a valve 29 whose anode circuit is connected via resistor 31 to one of the grids of a pentode 30 of which a second control grid is connected to the common output circuit of the valves 27. If solely one of the pentodes 27 is made conducting, the valve 29 is cut off, and the voltage increase over resistor 31 is sufficient to raise the voltage on one control electrode above the cut off valve, but the valve 30 conducts since the voltage applied to the second grid of the valve 30 via resistor 28 will be reduced solely by 20 volts. If, however, two of the pentodes 27 are conducting, the valve 29 is again cut off, but as the potential applied to the second grid is reduced to 60 volts, the valve 30 is cut off. If, therefore, a code signal is missing, the valve 30 becomes conducting and operates an alarm arrangement 35 and also applies a signal over lead 43 to control the circuit 19 to produce an error signal on the tape 25. The arrangement of Fig. 1 may be extended to a system in which numerals and characters are represented by groups of two or four-coded signals, and an error indication is produced with the production of one or three signals from the tape, by adding a second set of valves 29, 30 which are operated by pentodes 27 when only three signals are applied to the double-triodes 14. In a modification of Fig. 1, employing a seven-position code in which numerals and letters are represented by two or four code signals, all code combinations other than those defining the characters are arranged by the selective connection of the anode circuits of the double triodes 14 to operate a valve which controls an alarm circuit and/or an error-printing device.