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i) Frequency hopping: made in Hollywood

i) Frequency hopping: made in Hollywood

25.03.2019

 

George Antheil, a film composer in Hollywood, met actress Hedy Lamarr in 1940. Discussing torpedo control, Lamarr suggested that, by transmitting signals on rapidly changing frequencies, radio-guided weapons would be more resilient to detection and jamming. The sequence of frequencies would be known a priori by transmitter and receiver, but to the enemy the message would seem like noise. Antheil proposed coordinating the frequency changes the way he synchronized player pianos. This early version of frequency hopping thus used a piano roll to change between 88 frequencies (number of keys in a piano). The pair patented the idea in 1942, but it was ahead of its time. The Navy found the mechanism too bulky to fit in a torpedo. In 1957, however, the concept was taken up by engineers at Sylvania Electronic Systems. Their implementation, using electronics rather than piano rolls, became a basic tool for secure military communications. Other patents in frequency changing have cited Lamarr-Antheil as the basis of the field, and the concept underlies many anti-jamming devices used today. It has also been employed in wireless communication, e.g., in GSM. The patent was little-known till 1997, when the Electronic Frontier Foundation honored Lamarr with a special Pioneer Award. In 2005, the first Inventor's Day in German-speaking countries was held on her 92nd birthday.

(Entry suggested by Chandru Raman)

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