Patent GB-686439-A (GB)
Title: Improvements in and relating to apparatus for encoding electric signals
IPC: H03M1/00
Filed: 1951-06-13
Abstract: 686,439. Electric selective signalling. RADIOINDUSTRIE SOC. ANON. June 13, 1951 [June 14, 1950], No. 14038/51. Class' 40 (i) [Also in Group XL(c)] Binary code pulse groups representing numbers from 0 to 2<SP>n</SP>-1 by the presence or absence of n pulses, are generated by the application of a transient signal to a number of registering elements which include trigger circuits having one stable position and a return time equal to one code element interval or a multiple thereof, some of the trigger circuits being connected in cascade through differentiating circuits. As described seven different code groups 1-7, Fig. 1, are provided for, in which the group duration is T and each pulse duration is # = T/3. In one embodiment seven different registering elements are provided and operated by pulses applied to input leads 31-37, Fig. 3, respectively. Pulses applied to leads 31, 33, 37, to produce code groups 1, 3, 7 respectively, trigger multivibrators 41, 43, 47 having return times #, 2# and 3# respectively, determined by delay lines, Fig. 2 (not shown). To produce code groups 2, 4, 6, multivibrators 49, 51, 53 respectively produce pulses of duration #, # and 2# delayed respectively by intervals #, 2# and #. These delays are inserted by further multivibrators 42, 44, 45, to which the initiating pulses from leads 32, 34, 36 respectively are applied and from which delayed triggering voltages are derived by differentiation of their output pulses in circuits 48, 50, 52 to produce sharp positive trailing edge pulses. To produce code group 5 the initiating pulse from lead 35 is applied in parallel to circuit 45, similar to circuit 41, and circuit 55, 56, 57, similar to circuit 44, 50, 51. Their outputs are combined at point 58. The coder may be operated by closing all the input switch contacts 29'-29' to apply the initiating pulse to all the registering elements. simultaneously, the desired output switch contact of the series 38'-38' being closed to select the code output. Alternatively all the output contacts may remain closed and the initiating pulse applied to the appropriate registering element through a selected one of the input contacts. For quantizing and coding a continuously varying signal the input channels of the coder 63, Fig. 4, are fed through amplifiers 62 from the target electrodes 29'-29' of a cathode-ray tube 59. The beam is switched on by recurrent pulses, of interval T, from a generator. 60 and the deflecting electrodes have the varying signal from source 61 applied thereto. Each brightening pulse causes a pulse to be generated on one of the target electrodes and the generation of the appropriate code pulse group at the common output terminal 30. In a modification, all the coding is performed by three multivibrators 65, 66, 67, Fig. 5, connected in cascade through differentiating circuits 68, 69, and each producing pulses of duration #. The initiating pulse'is applied to one of the input terminals 31-37 which are each so connected to the input sides of one, two or three of the multivibrators, that the desired output code group appears at the output terminal 30. In a similar arrangement, Fig. 6 (not shown), all the multivibrators produce pulses for each initiating pulse and the code selection is performed by gating valves connected to their outputs in a similar manner to the connections of terminals 31-37, Fig. 5.