GB500831A - Improvements in or relating to secret telegraphy - Google Patents

Abstract

500,831. Type - printing telegraphy. RUGH, H. O. Jan. 12, 1938, No. 1057. [Class 40 (iii)] Ciphering is effected by jumbling the elements of a Baudot signal combination in an order which is varied at arbitrary intervals. The description applies to a 3-impulse code, the segments 4, 5 of the distributers being used solely for codechanging impulses, but a code employing more than three impulses may be employed. Depression of an ordinary key 13 in the transmitter T connects selected segments of the transmitting distributer 30 to the battery 12, and also closes contacts 16 by means of a ratchet and cam 15, 19 to release the start-stop arms 31, 36 at both stations. The three signal elements are jumbled in an order which is varied when switch 29 is moved one step, through ratchet 58, on depression of key 20 and consequent operation of pawl 55. The switch 29 is restored to its zero position when key 21 is depressed to release pawl 78. At the receiving station R the decoding switch 44 is similarly operated under the control of ratchet 67, bars 61, 70, and receiving magnets 4, 5, which respond to signals set up by the transmitter keys 20, 21. Alternatively a message recorded in code can be decoded by passing it a sufficient number of times through a local transmitter and receiver constructed as shown.