Eletoz/Vie Patented Sept
Sept. 7, 1926. 1,598,673 O. B. BLACKWELL ET AL SECRECY COMMUNICATION SYSTEM Filed Dec. 18, 1920 R (2AA%aeaeAA 8 eletoz/vie Patented Sept. 7, 1926. 1,598,673 UNITED STATES PATENT office. OTTO B. BLACKWELL, OF GARDEN CITY, NEW YORK; DE Loss K. MARTIN, or oRANGE, NEW JERSEY; AND GILBERT S. VERNAM, OF BROOKLYN, NEw YoRK, AssGNORs TO AMERICAN TELEPHONE AND TELEGRAPH. COMPANY, A CoRFoRATION of NEW YORK, sECREGY coMMUNICATIoN sYSTEM. Application filed December 18, 1920. Serial No. 431,721. This invention relates to a signaling sys pear more fully from the detailed descrip 50 tem wherein signals are transmitted by the tion hereinafter given. agency of a high frequency wave modu The arrangements of the invention are ill lated in accordance with said signals, and lustrated in the accompanying drawing, in more particularly to a signalling system em the figure of which is shown a sendingsta ploying a plurality of high frequency tion of a system embodying the invention. 35 waves. It is the object of the invention to In the arrangements of the drawing are rovide a system of communication where shown four low frequency channels 1, 2, 3 y secret communications between stations and 4 from which the low frequency sig 10 may be had to the end that stations, other nals, such as four telephone messages, may than those designed to receive, may not re be transmitted through modulating appara 60 ceive complete, intelligible signals. tus out over a transmission line L. The Heretofore in certain types of signaling modulating apparatus is shown schemati systems, in which a high frequency wave is cally and includes the modulators M., M., 15 utilized as the agency for transmitting the Me and Ma, with which are associated the signals, he signals have been transmitted high frequency sources A, B, C, and D, 65 by electromagnetic waves of a definite high which are of suitable different frequencies.
[Show full text]