Radio age research, manufacturing, communications, broadcasting, television (1941)

see the beach, and the houses. . . . We dropped our cable-cuttinj? shears attached to a grapnel over- board, attached to a long wire rope. Back and forth \ve cruised, trolling not for fish, but for any of the cables we might run across. The thrill was almost as great as fish- ing for bluefish." (.From pp. 32-3, German Subs hi Yankee Waters, by Henry .J. James, Gotham House, 1940.) The actual damage to the cables cut by the U-151, the author of the book says, was "relatively negligi- ble" because only tico were cut: the Commercial Cable Company's #4 Canso cable—Nova Scotia to New York—and another, owned by the All-America Cable Company, run- ning from New York to Colon I A cable can be cut, and its repair is difficult. A radiotelegraph circuit may be "jammed." but it cannot be put out of commission permanently. Jamming could bring reprisals to affect enemy circuits, and this is one reason why radiotelegraph fa- cilities are comparatively secure. A cable is not safe merely be- cause it lies on the bed of an ocean. Proof is given in the Chief Signal Officer's report referred to above: Urges Radiotelegraphy "It was concluded that complete severance of cable communication by the enemy was not impossible." In the same report Colonel Edgar Russell, who later was to become Brigadier General and Chief Signal Officer, is quoted from a memoran- dum dated August 15, 1917: " 'From my own experience in cable engineering I am satisfied that it would be entirely practicable for the enemy to cut some or all of the cables whenever he considers it important enough to do so.' " Five days later he wrote to the Commander-in-Chief of the Amer- ican Expeditionary Forces: " "There is no question of the grave situation in which we may find ourselves as a result of exten- sive cable cutting which, in the be- lief of all the cable authorities we have consulted, may be easily ef- fected by the enemy. The enormous importance of immediate provision of reliable and extensive trans- Atlantic radiotelegraph service is therefore evident.' " Thank Heaven that RCA heeded this warning, and provided emer- gency radio telegraph capacity which stands ready for use at any time! Confirmation of the work of the lJ-151 is also found in the report of the Chief Signal Officer: "Information furnished by the Navy concerning the enemy's inten- tions seemed to be well founded, for while the German submarines were operating on the Atlantic coast of the United States, two submarine cables were cut about 100 miles from New York, one a cable from New York to Canso, Nova Scotia, which stopped working at 12:35 p. m. on May 28, the other a cable from New York to Colon which be- gan to fail at 3:30 p.m. on May 28th and went out of commission entirely at 9:30 p.m." If an enemy interceptor is or- dered to copy radiotelegraph sig- nals between two Allied points, he soon learns he cannot do it with por- table equipment. When he attempts to follow the daily shifts of a single circuit, he must obtain complete tuning equipment for as many wavelengths as the total in use at both ends; he must, since he cannot personally operate on sevei-al wave- lengths, monitor and record all sta- tions continuously. He must also be near supplies and maintenance materials—which means he is in a disadvantageous location, for Allied antennas are aimed at each othei-, not at him. From his records, he must dupli- cate whatever printer, multiplex, or coding devices are in use, and learn to distinguish between one type of signal—or combination of signals— and all the rest, and he also must follow the changes in them quickly. This work, even with receivers of the highest order, must necessarily be done with an inferior signal. Radiotelegr.'qih circuits are engi- neered over their ether routes as well as in the terminal offices. Everything in a modern radiotele- graph company, after years of prac- tical operation with all types of equipment, is there because it helps to maintain maximum efficiency in propagation between two desired points on the earth's surface. Every phase of operation—switching tech- nique, signal transcription, clerical work, novel apparatus—is combined for the fastest, most accurate signal transmission over the desii-ed path. If, having better ecjuipment—a premise conceded only for the sake of discussion—the enemy intercept- or is able to receive, record, and translate all our transmissions, on all our circuits, in both directions, he still cannot duplicate one of the most important factors: the engi- neering and operating technique of a communications company which for more than two decades, has been schooling itself by accomplishment day and night, seven days a week. Speed of communication is a mili- tary advantage. Enemy delay is also an important secrecy factor. One message route from New York to Cairo, Egypt, is via cable to London. From London, it is re- transmitted, by cable or radio, to its final destination. Radio's Advantages By radio, the message would go directly from New York to Cairo. If the cable between New York and London were tapped, a cable- gram from New York to Cairo would be in enemy hands before the addressee received it! The wide frequency channels of radiotelegraphy allow the design engineer freedom in his choice of control equipment. Since some se- crecy systems depend upon a sacri- fice of frequency-band width, they THIS high-spe:ed rcac printer pre- pares MESSAGES FOR AUTOMATIC TRANS- MISSION BY RADIOTELEGRAPHY ACROSS CONTINENTS AND SEAS. RADIO AGE 191