GB679390A - Improvements in or relating to electric signalling systems for coded trains of impulses - Google Patents

Abstract

679,390. Electrical calculating-apparatus. SOC D'ELECTRONIQUE ET D'AUTOMATISME. Feb. 16, 1950 [Feb. 17, 1949], No. 4028/50. Class 106 (i). [Also in Group XL (c)] An encoding circuit for use in electric systems for signalling coded trains of electric pulses, comprises a quadripole which, upon application thereto of one or more transient signals of short duration compared with the propagation constant of the quadripole, delivers a pulse train of regular periodicity, each pulse representing a term of a numerical series of the form: (in which B represents a radix), the quadripole including means for adjusting or automatically controlling the amplitudes of the pulses to correspond to the values of the coefficients a of the series. In one embodiment a train of short pulses is applied to the input of a known type of counter 1, Fig. 1, which advances by one stage for each pulse applied and delivers an output pulse from each stage in turn. Impedances 11 such as continuously-variable or tapped resistors, varistors, thermistors, gas-filled or vacuum tubes, or cathode-ray tubes of the multipletarget type, are adjusted or automatically controlled to determine the amplitudes of the respective pulses which are fed to a common conductor 4 and may be applied to the control grid of a valve 7 for re-shaping. In the case where radix B=2 (i.e. the Binary System), the impedances 11 are replaced by on-off switches. In a modification the pulse counter 1 is replaced by an artificial delay line tapped at regular intervals for connection to the parallel impedances. A single input pulse is then sufficient to generate a coded output pulse train, but in this version coded pulse trains can be applied to the input and a multiplication performed. Switching arrangements, Figs. 4 and 5 (not shown), may be used in this modification to avoid disturbances due to reflection or parasitic currents. In another embodiment, the device for setting up the required coefficients a is a binaryscale pulse counter 16, Fig. 6, which may itself be set up by a coded pulse train. The parallel paths from the delay line 10 are connected, via resistors 11, to the control grids of tubes 12, whilst the blocking voltages representing the values of the coefficients a are provided by the device 16, and are applied to the suppressor grids 17. Regenerating pulses are applied to the screen grids, and the output pulses are developed across a load 6. In one modification of this embodiment the delay line 10 is split up into portions which are linked together by connections across the control grids of the tubes, Fig. 7 (not shown). In another modification the delay line is replaced by a simple mechanical, electro-mechanical or electronic step-by-step device which sends out pilot pulses successively to the control grids of the tubes which, in this case, are normally blocked oscillators and are triggered by the pilot pulses from the step-by-step device. French Specification 985,051 is referred to.