SCRAMBLED SPEECH

Radio Record, Volume I, Issue 43, 11 May 1928, Page 16

SCRAMBLED SPEECH

WONDERFUL NEW DEVICE A METHOD IF SECRECY. The American Iclephore and Tele phone Comipany’s new process for scrambling and unscrambling speech and music, which was demonstrated in Washington on February 24, waz exhibited publicly in New York for the first time recently at the monthly meeting of the New York TJilectrical Society. The device promises to render speech by radio telephony unintelligible except to those who have a special apparatus. Thus secrecy may be introduced into radio telephonic communication. Sounds which enter the scrambling bystem as hisses or whistle come out as hollow, leonine roars. That which enfets as deep bass comes cut shrill and

ig turned upside down, so that low is high, medium iow is medium high, while the exact middle of the register remains unchanged. The apparatus, which was demonstrated by Sergius P. Grace, general commercial engincer of the Leil Telephone Laboratorics, turug luman speech inside ont. "Chicago," said Mr. Grace in his own voice at the transmitting end of the apparatus. "Si-kay-be," roared the loudspeakers which aniplified the twisted language. Process is Reversed, The engineer then uttered the syllables ‘‘Piay-a-feen crink-a-nepe," and the device translated those raudom sounds into ‘telephone compar y.’? Mr Grace figured out on paper, with the aid of mathematics, that the name of his friend Bennett would be scrainbicd into doughnut." He spoke the word "Doughnut" and the loudspeaker shrieked ‘Bennett.’ piercing. The whole scele ot ow

Sound waves of 5000 frequencics a second are about the highest that the ear can hear. ‘These are scrambled to about fifty frequenzies a second, the deepest audible tones, Frequencies of 4000 a second, still very high. are changed to about L000 a second; 5000 a second to 2000 a second, while those which are 2500 a second remain wi changed. Tt was explained that the sound waves actuated a current, as in ordinary tclephoning. This current, modulated by the speech, entered an electrical system which was running at 5000 cycles a second. According to Mr. Grace, it would take algebra and calculus to explain how it is that the treble is turned into bass and the bass into treble and how all but the middle tones are thrown into reverse. Ased if the purpose was to keep transatlantic telephone speech in cipher as it crosses the ocean, Mr. Grace said :--- "No, that ism’t it. The purpose was to find out if sound could be sevembled

and unscrambled this way and just how to do it. If the time comes when we want to use it in the transatlantic service or in any other way, we have it.’’ : Tests Made Few Years Ago. A few years ago the American Telephone and Telegraph Company carried of some experiments of this kind between Catalina Island and Los Angeles. At that time there was a hue and cry about the "radio trust,’? and it was predicied that the scrambling and unscrambling device would be used to modify broadcasting bv sending scrambled programmes which would only be made intelligible to those who owned patent unscramblers. A_ telephone official was asked about this. He said: "The company is not the least interested in that. I doubt if anything of the kind ever will come to pass. ‘The public is too well broken in to broadcasting and getting it free. They would never stand for being conipelled to buy the unscrambling sets."

Mr. Grace said that the instrument undoubtedly would have a_ military value as a methou of communication which the enemy could not intercept. He said that the scrambling. and ut‘scrambling instruments could be regulated so that the euwemy would not have one chatice in 2 million of listening in successfau,.