GB176379A - Arrangement for increasing the speed of telegraphing over long lines - Google Patents

Abstract

176,379. Wagner, K. W., and K³pfm³ller, K. March 4, 1921, [Convention date]. Void [Published under Sect. 91 of the Act]. Thermionic relays. - To increase the speed of telegraphing over long lines such as submarine cables, differentiating circuits and amplifiers are so connected and dimensioned that the effect upon the receiving- apparatus corresponds to the second or a higher differential coefficient of the curve of current at the end of the line unprovided with auxiliary arrangements. When a constant electromotive force is applied to a line, the current rises to its maximum value in the manner shown by the curve, .Fig. 1, in which current strength is plotted against time. In known apparatus, involving the use of terminal condensers, or inductance bridging tha receiving- apparatus, the effect on the receiver depends upon the rate of change of current in the line, as indicated by the curve, Fig. 4, obtained from that in Fig. 1 by differentiating with respect to time. The present invention makes the effect in the receiver depend upon the second or a higher differentiation, the corresponding timecurrent curve becoming steeper for each successive differentiation, as shown by the curves #2, #3, #4, Fig. 5, corresponding respectively with the second, third, and fourth differentiations. Amplifiers are used to compensate for loss of amplitude by differentiation, and arrangement mav be made whereby amplification occurs together with, or subsequent to, the differentiation. Fig. 7 shows an arrangement wherein the effect in the receiver s depends upon the third differentiation. K are terminal condensers at the end of the line. K<0> is a condenser, L a coil, r a resistance, and V an amplifier to which the receiver is connected. The Specification gives rules governing the relative values of the various impedances. To make the receiver actuation depend upon the second differential, condenser K‹ and resistance r are omitted. The coils L may be replaced by transformers. Arrangements are also described from which the condensers K are absent. To give simultaneous differentiation and amplification, thermionic valves in cascade are used, the coupling between the plate of one valve and the grid of the next being by means of a differentiating circuit. Fig. 10 shows a suitable arrangement, K being a condenser and r<1>, r<2> resistances. Several modified arrangements are described. In one modification, separate sources of electromotive force are provided to regulate the grid potentials.