GB412732A - Improvements in or relating to multiplex telegraph systems - Google Patents

Abstract

412,732. Diplex telegraphy. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.- (Assignees of Mathes, R. E. ; 755, Belvidere Avenue, Westfield, New Jersey, U.S.A.) April 12, 1933, No. 10962. Convention date, April 13, 1932. [Classes 40 (iii) and 40 (v).] In a diplex line or wireless telegraph system using morse or like code characters of unequal length, the first half of each dot period is allotted to one channel and the second half to the other. Two automatic transmitters feed an aerial through a distributer which allocates the line time accordingly (Figs. 1, 2, not shown). At the receiver the block signals a are rectified by the valve 20 as at b and produce pulses as at c through a valve 25 and shaping and delay circuit 22, 23, to synchronize the multi-vibrator which produces continuous impulses as at d. These impulses are applied to valves 26, 27 of the first channel through condensers which shape them into pulses as shown at h, f. The valve 26 is biassed as at h to respond to the pulses so that, in the absence of marking signals, it takes control of the flip-flop device 28, and spacing polarity is consequently applied as at j2, j4 to the receiving-apparatus R of the first channel. The valve 27, on the other hand, receives the combined effects g of the vibrator pulses f from the conductor 37 and signals c from the valve 29, and is biassed as at f so that it cannot respond to vibrator pulses f alone or to signal impulses c alone, but can respond to combinations such as gl, g3, of these two. The circuit constants are such that the received signals paralyze valve 25 and so act upon the grid of valve 27 by removing the negative voltage-drop from resistance 30 upon blockage of valve 29. When valve 27 responds it overpowers the effect of the valve 26 and takes control of the flip-flop 28, so that a marking signal is sent to the apparatus R ; and since the impulses f, h are so timed that the apparatus is receptive during only the first half of each dot period, the signals at R are prolonged to full length as at j. Inductance 23 delays the pulses c so as to give the signals time to attain a steady state. The second channel is fed through the leads 38, 39, and is receptive during the second half of each dot period under the control of the same multi-vibrator 35.